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Sample records for volcano observatory yvo

  1. The origin of the Hawaiian Volcano Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Dvorak, John [University of Hawaii' s Institute for Astronomy (United States)

    2011-05-15

    I first stepped through the doorway of the Hawaiian Volcano Observatory in 1976, and I was impressed by what I saw: A dozen people working out of a stone-and-metal building perched at the edge of a high cliff with a spectacular view of a vast volcanic plain. Their primary purpose was to monitor the island's two active volcanoes, Kilauea and Mauna Loa. I joined them, working for six weeks as a volunteer and then, years later, as a staff scientist. That gave me several chances to ask how the observatory had started.

  2. Decision Analysis Tools for Volcano Observatories

    Science.gov (United States)

    Hincks, T. H.; Aspinall, W.; Woo, G.

    2005-12-01

    Staff at volcano observatories are predominantly engaged in scientific activities related to volcano monitoring and instrumentation, data acquisition and analysis. Accordingly, the academic education and professional training of observatory staff tend to focus on these scientific functions. From time to time, however, staff may be called upon to provide decision support to government officials responsible for civil protection. Recognizing that Earth scientists may have limited technical familiarity with formal decision analysis methods, specialist software tools that assist decision support in a crisis should be welcome. A review is given of two software tools that have been under development recently. The first is for probabilistic risk assessment of human and economic loss from volcanic eruptions, and is of practical use in short and medium-term risk-informed planning of exclusion zones, post-disaster response, etc. A multiple branch event-tree architecture for the software, together with a formalism for ascribing probabilities to branches, have been developed within the context of the European Community EXPLORIS project. The second software tool utilizes the principles of the Bayesian Belief Network (BBN) for evidence-based assessment of volcanic state and probabilistic threat evaluation. This is of practical application in short-term volcano hazard forecasting and real-time crisis management, including the difficult challenge of deciding when an eruption is over. An open-source BBN library is the software foundation for this tool, which is capable of combining synoptically different strands of observational data from diverse monitoring sources. A conceptual vision is presented of the practical deployment of these decision analysis tools in a future volcano observatory environment. Summary retrospective analyses are given of previous volcanic crises to illustrate the hazard and risk insights gained from use of these tools.

  3. Abstract volume for the 2016 biennial meeting of the Yellowstone Volcano Observatory

    Science.gov (United States)

    Lowenstern, Jacob B.

    2016-10-20

    IntroductionEvery two years, scientists, natural resource managers, outreach specialists, and a variety of other interested parties get together for the biennial meeting of the Yellowstone Volcano Observatory (YVO). Each time, the theme varies. In past years, we have focused the meeting around topics including monitoring plans, emergency response, geodesy, and outreach. This year, we spent the first half-day devoted to recent research results, plans for upcoming studies, and geothermal monitoring. On the second day, our focus switched to eruption precursors, particularly as they apply to large caldera systems.Very few large explosive eruptions from caldera systems have taken place in recorded history. Therefore, there are few empirical data with which to characterize the nature of volcanic unrest that might precede eruptions with volcano explosivity index (VEI) of six or greater. For this reason, we set up a series of talks that explore what we know and don’t know about large eruptions. We performed an informal expert elicitation (a frequently used method to characterize expert opinion) with a small number of our colleagues, which served as the basis for a productive discussion session.This short volume of abstracts and extended abstracts provides a summary of the presentations made at the YVO meeting held in Mammoth Hot Springs, Wyoming, on May 10–11, 2016.

  4. Linking space observations to volcano observatories in Latin America: Results from the CEOS DRM Volcano Pilot

    Science.gov (United States)

    Delgado, F.; Pritchard, M. E.; Biggs, J.; Arnold, D. W. D.; Poland, M. P.; Ebmeier, S. K.; Wauthier, C.; Wnuk, K.; Parker, A. L.; Amelug, F.; Sansosti, E.; Mothes, P. A.; Macedo, O.; Lara, L.; Zoffoli, S.; Aguilar, V.

    2015-12-01

    Within Latin American, about 315 volcanoes that have been active in the Holocene, but according to the United Nations Global Assessment of Risk 2015 report (GAR15) 202 of these volcanoes have no seismic, deformation or gas monitoring. Following the 2012 Santorini Report on satellite Earth Observation and Geohazards, the Committee on Earth Observation Satellites (CEOS) has developed a 3-year pilot project to demonstrate how satellite observations can be used to monitor large numbers of volcanoes cost-effectively, particularly in areas with scarce instrumentation and/or difficult access. The pilot aims to improve disaster risk management (DRM) by working directly with the volcano observatories that are governmentally responsible for volcano monitoring, and the project is possible thanks to data provided at no cost by international space agencies (ESA, CSA, ASI, DLR, JAXA, NASA, CNES). Here we highlight several examples of how satellite observations have been used by volcano observatories during the last 18 months to monitor volcanoes and respond to crises -- for example the 2013-2014 unrest episode at Cerro Negro/Chiles (Ecuador-Colombia border); the 2015 eruptions of Villarrica and Calbuco volcanoes, Chile; the 2013-present unrest and eruptions at Sabancaya and Ubinas volcanoes, Peru; the 2015 unrest at Guallatiri volcano, Chile; and the 2012-present rapid uplift at Cordon Caulle, Chile. Our primary tool is measurements of ground deformation made by Interferometric Synthetic Aperture Radar (InSAR) but thermal and outgassing data have been used in a few cases. InSAR data have helped to determine the alert level at these volcanoes, served as an independent check on ground sensors, guided the deployment of ground instruments, and aided situational awareness. We will describe several lessons learned about the type of data products and information that are most needed by the volcano observatories in different countries.

  5. Chasing lava: a geologist's adventures at the Hawaiian Volcano Observatory

    Science.gov (United States)

    Duffield, Wendell A.

    2003-01-01

    A lively account of the three years (1969-1972) spent by geologist Wendell Duffield working at the Hawaiian Volcano Observatory at Kilauea, one of the world's more active volcanoes. Abundantly illustrated in b&w and color, with line drawings and maps, as well. Volcanologists and general readers alike will enjoy author Wendell Duffield's report from Kilauea--home of Pele, the goddess of fire and volcanoes. Duffield's narrative encompasses everything from the scientific (his discovery that the movements of cooled lava on a lava lake mimic the movements of the earth's crust, providing an accessible model for understanding plate tectonics) to the humorous (his dog's discovery of a snake on the supposedly snake-free island) to the life-threatening (a colleague's plunge into molten lava). This charming account of living and working at Kilauea, one of the world's most active volcanoes, is sure to be a delight.

  6. Hawaiian Volcano Observatory seismic data, January to March 2009

    Science.gov (United States)

    Nakata, Jennifer S.; Okubo, Paul G.

    2010-01-01

    This U.S. Geological Survey (USGS), Hawaiian Volcano Observatory (HVO) summary presents seismic data gathered during January–March 2009. The seismic summary offers earthquake hypocenters without interpretation as a source of preliminary data and is complete in that most data for events of M≥1.5 are included. All latitude and longitude references in this report are stated in Old Hawaiian Datum.

  7. Developing monitoring capability of a volcano observatory: the example of the Vanuatu Geohazards Observatory

    Science.gov (United States)

    Todman, S.; Garaebiti, E.; Jolly, G. E.; Sherburn, S.; Scott, B.; Jolly, A. D.; Fournier, N.; Miller, C. A.

    2010-12-01

    Vanuatu lies on the Pacific 'Ring of Fire'. With 6 active subaerial and 3 submarine (identified so far) volcanoes, monitoring and following up their activities is a considerable work for a national observatory. The Vanuatu Geohazards Observatory is a good example of what can be done from ‘scratch’ to develop a volcanic monitoring capability in a short space of time. A fire in June 2007 completely destroyed the old observatory building and many valuable records leaving Vanuatu with no volcano monitoring capacity. This situation forced the Government of Vanuatu to reconsider the structure of the hazards monitoring group and think about the best way to rebuild a complete volcano monitoring system. Taking the opportunity of the re-awakening of Gaua volcano (North of Vanuatu), the Vanuatu Geohazards section in partnership with GNS Science, New Zealand developed a new program including a strategic plan for Geohazards from 2010-2020, the installation of a portable seismic network with real-time data transmission in Gaua, the support of the first permanent monitoring station installation in Ambrym and the design and implementation of volcano monitoring infrastructure and protocol. Moreover the technology improvements of the last decade and the quick extension of enhanced communication systems across the islands of Vanuatu played a very important role for the development of this program. In less than one year, the implementation of this program was beyond expectations and showed considerable improvement of the Vanuatu Geohazards Observatory volcano monitoring capability. In response to increased volcanic activity (or unrest) in Ambae, the Geohazards section was fully capable of the installation of a portable seismic station in April 2010 and to follow the development of the activity. Ultimately, this increased capability results in better and timelier delivery of information and advice on the threat from volcanic activity to the National Disaster Management Office and

  8. Seismic instrumentation plan for the Hawaiian Volcano Observatory

    Science.gov (United States)

    Thelen, Weston A.

    2014-01-01

    The seismic network operated by the U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) is the main source of authoritative data for reporting earthquakes in the State of Hawaii, including those that occur on the State’s six active volcanoes (Kīlauea, Mauna Loa, Hualālai, Mauna Kea, Haleakalā, Lō‘ihi). Of these volcanoes, Kīlauea and Mauna Loa are considered “very high threat” in a report on the rationale for a National Volcanic Early Warning System (NVEWS) (Ewert and others, 2005). This seismic instrumentation plan assesses the current state of HVO’s seismic network with respect to the State’s active volcanoes and calculates the number of stations that are needed to upgrade the current network to provide a seismic early warning capability for forecasting volcanic activity. Further, the report provides proposed priorities for upgrading the seismic network and a cost assessment for both the installation costs and maintenance costs of the improved network that are required to fully realize the potential of the early warning system.

  9. Modernization of the USGS Hawaiian Volcano Observatory Seismic Processing Infrastructure

    Science.gov (United States)

    Antolik, L.; Shiro, B.; Friberg, P. A.

    2016-12-01

    The USGS Hawaiian Volcano Observatory (HVO) operates a Tier 1 Advanced National Seismic System (ANSS) seismic network to monitor, characterize, and report on volcanic and earthquake activity in the State of Hawaii. Upgrades at the observatory since 2009 have improved the digital telemetry network, computing resources, and seismic data processing with the adoption of the ANSS Quake Management System (AQMS) system. HVO aims to build on these efforts by further modernizing its seismic processing infrastructure and strengthen its ability to meet ANSS performance standards. Most notably, this will also allow HVO to support redundant systems, both onsite and offsite, in order to provide better continuity of operation during intermittent power and network outages. We are in the process of implementing a number of upgrades and improvements on HVO's seismic processing infrastructure, including: 1) Virtualization of AQMS physical servers; 2) Migration of server operating systems from Solaris to Linux; 3) Consolidation of AQMS real-time and post-processing services to a single server; 4) Upgrading database from Oracle 10 to Oracle 12; and 5) Upgrading to the latest Earthworm and AQMS software. These improvements will make server administration more efficient, minimize hardware resources required by AQMS, simplify the Oracle replication setup, and provide better integration with HVO's existing state of health monitoring tools and backup system. Ultimately, it will provide HVO with the latest and most secure software available while making the software easier to deploy and support.

  10. Development of Alaska Volcano Observatory Seismic Networks, 1988-2008

    Science.gov (United States)

    Tytgat, G.; Paskievitch, J. F.; McNutt, S. R.; Power, J. A.

    2008-12-01

    The number and quality of seismic stations and networks on Alaskan volcanoes have increased dramatically in the 20 years from 1988 to 2008. Starting with 28 stations on six volcanoes in 1988, the Alaska Volcano Observatory (AVO) now operates 194 stations in networks on 33 volcanoes spanning the 2000 km Aleutian Arc. All data are telemetered in real time to laboratory facilities in Fairbanks and Anchorage and recorded on digital acquisition systems. Data are used for both monitoring and research. The basic and standard network designs are driven by practical considerations including geography and terrain, access to commercial telecommunications services, and environmental vulnerability. Typical networks consist of 6 to 8 analog stations, whose data can be telemetered to fit on a single analog telephone circuit terminated ultimately in either Fairbanks or Anchorage. Towns provide access to commercial telecommunications and signals are often consolidated for telemetry by remote computer systems. Most AVO stations consist of custom made fiberglass huts that house the batteries, electronics, and antennae. Solar panels are bolted to the south facing side of the huts and the seismometers are buried nearby. The huts are rugged and have allowed for good station survivability and performance reliability. However, damage has occurred from wind, wind-blown pumice, volcanic ejecta, lightning, icing, and bears. Power is provided by multiple isolated banks of storage batteries charged by solar panels. Primary cells are used to provide backup power should the rechargable system fail or fall short of meeting the requirement. In the worst cases, snow loading blocks the solar panels for 7 months, so sufficient power storage must provide power for at least this long. Although primarily seismic stations, the huts and overall design allow additional instruments to be added, such as infrasound sensors, webcams, electric field meters, etc. Yearly maintenance visits are desirable, but some

  11. 2014 volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Cameron, Cheryl E.; Dixon, James P.; Neal, Christina A.; Waythomas, Christopher F.; Schaefer, Janet R.; McGimsey, Robert G.

    2017-09-07

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest or suspected unrest, and seismic events at 18 volcanic centers in Alaska during 2014. The most notable volcanic activity consisted of intermittent ash eruptions from long-active Cleveland and Shishaldin Volcanoes in the Aleutian Islands, and two eruptive episodes at Pavlof Volcano on the Alaska Peninsula. Semisopochnoi and Akutan volcanoes had seismic swarms, both likely the result of magmatic intrusion. The AVO also installed seismometers and infrasound instruments at Mount Cleveland during 2014.

  12. 2013 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Dixon, James P.; Cameron, Cheryl; McGimsey, Robert G.; Neal, Christina A.; Waythomas, Chris

    2015-08-14

    The Alaska Volcano Observatory (AVO) responded to eruptions, volcanic unrest or suspected unrest, and seismic events at 18 volcanic centers in Alaska during 2013. Beginning with the 2013 AVO Summary of Events, the annual description of the AVO seismograph network and activity, once a stand-alone publication, is now part of this report. Because of this change, the annual summary now contains an expanded description of seismic activity at Alaskan volcanoes. Eruptions occurred at three volcanic centers in 2013: Pavlof Volcano in May and June, Mount Veniaminof Volcano in June through December, and Cleveland Volcano throughout the year. None of these three eruptive events resulted in 24-hour staffing at AVO facilities in Anchorage or Fairbanks.

  13. The Hawaiian Volcano Observatory: a natural laboratory for studying basaltic volcanism: Chapter 1 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Tilling, Robert I.; Kauahikaua, James P.; Brantley, Steven R.; Neal, Christina A.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    In the beginning of the 20th century, geologist Thomas A. Jaggar, Jr., argued that, to fully understand volcanic and associated hazards, the expeditionary mode of studying eruptions only after they occurred was inadequate. Instead, he fervently advocated the use of permanent observatories to record and measure volcanic phenomena—at and below the surface—before, during, and after eruptions to obtain the basic scientific information needed to protect people and property from volcanic hazards. With the crucial early help of American volcanologist Frank Alvord Perret and the Hawaiian business community, the Hawaiian Volcano Observatory (HVO) was established in 1912, and Jaggar’s vision became reality. From its inception, HVO’s mission has centered on several goals: (1) measuring and documenting the seismic, eruptive, and geodetic processes of active Hawaiian volcanoes (principally Kīlauea and Mauna Loa); (2) geological mapping and dating of deposits to reconstruct volcanic histories, understand island evolution, and determine eruptive frequencies and volcanic hazards; (3) systematically collecting eruptive products, including gases, for laboratory analysis; and (4) widely disseminating observatory-acquired data and analysis, reports, and hazard warnings to the global scientific community, emergency-management authorities, news media, and the public. The long-term focus on these goals by HVO scientists, in collaboration with investigators from many other organizations, continues to fulfill Jaggar’s career-long vision of reducing risks from volcanic and earthquake hazards across the globe.

  14. 2015 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Dixon, James P.; Cameron, Cheryl E.; Iezzi, Alexandra M.; Wallace, Kristi

    2017-09-28

    The Alaska Volcano Observatory (AVO) responded to eruptions, volcanic unrest or suspected unrest, and seismic events at 14 volcanic centers in Alaska during 2015. The most notable volcanic activity consisted of continuing intermittent ash eruptions from Cleveland and Shishaldin volcanoes in the Aleutian Islands. Two eruptive episodes, at Veniaminof and Pavlof, on the Alaska Peninsula ended in 2015. During 2015, AVO re-established the seismograph network at Aniakchak, installed six new broadband seismometers throughout the Aleutian Islands, and added a Multiple component Gas Analyzer System (MultiGAS) station on Augustine.

  15. Tectono-Magmatic Investigations with Societal Implications: Progress on the Tanzania Volcano Observatory (TZVOLCANO)

    Science.gov (United States)

    Stamps, D. S.; Saria, E.; Jones, J. R.; Daniels, M. D.; Mencin, D.

    2016-12-01

    Cross-domain collaborations amongst geoscientists and technologists become necessary when the scientific and societal needs surpass current cyberinfrastructure and data access mechanisms. For example, characterizing magma movement and fault-slip in real-time on and around active volcanoes is crucial for volcanic hazards and risk assessment. The necessary real-time positioning sensors are available, however the technological capacity for import, export, and analysis are in the early phases of development. Here, we present progress on the new, multi-national Tanzania Volcano Observatory (TZVOLCANO) initiated in June 2016. The observatory currently utilizes the pilot EarthCube cyberinfrastructure "Cloud-hosted Real-time Data Services for the Geosciences" (CHORDS) to visualize near-real time positioning data (http://tzvolcano.chordsrt.com/) that are accessible through the UNAVCO real-time archive. Our work aligns with the "resilience to disasters" and "holistic disaster risk management at all levels" targets of Sustainable Development Goal 11: Sustainable Cities and Communities.

  16. 2012 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Herrick, Julie A.; Neal, Christina A.; Cameron, Cheryl E.; Dixon, James P.; McGimsey, Robert G.

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, or suspected unrest at 11 volcanic centers in Alaska during 2012. Of the two verified eruptions, one (Cleveland) was clearly magmatic and the other (Kanaga) was most likely a single phreatic explosion. Two other volcanoes had notable seismic swarms that probably were caused by magmatic intrusions (Iliamna and Little Sitkin). For each period of clear volcanic unrest, AVO staff increased monitoring vigilance as needed, reviewed eruptive histories of the volcanoes in question to help evaluate likely outcomes, and shared observations and interpretations with the public. 2012 also was the 100th anniversary of Alaska’s Katmai-Novarupta eruption of 1912, the largest eruption on Earth in the 20th century and one of the most important volcanic eruptions in modern times. AVO marked this occasion with several public events.

  17. 2010 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Neal, Christina A.; Herrick, Julie; Girina, O.A.; Chibisova, Marina; Rybin, Alexander; McGimsey, Robert G.; Dixon, Jim

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest or suspected unrest at 12 volcanic centers in Alaska during 2010. The most notable volcanic activity consisted of intermittent ash emissions from long-active Cleveland volcano in the Aleutian Islands. AVO staff also participated in hazard communication regarding eruptions or unrest at seven volcanoes in Russia as part of an ongoing collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  18. General Purpose Real-time Data Analysis and Visualization Software for Volcano Observatories

    Science.gov (United States)

    Cervelli, P. F.; Miklius, A.; Antolik, L.; Parker, T.; Cervelli, D.

    2011-12-01

    In 2002, the USGS developed the Valve software for management, visualization, and analysis of volcano monitoring data. In 2004, the USGS developed similar software, called Swarm, for the same purpose but specifically tailored for seismic waveform data. Since then, both of these programs have become ubiquitous at US volcano observatories, and in the case of Swarm, common at volcano observatories across the globe. Though innovative from the perspective of software design, neither program is methodologically novel. Indeed, the software can perform little more than elementary 2D graphing, along with basic geophysical analysis. So, why is the software successful? The answer is that both of these programs take data from the realm of discipline specialists and make them universally available to all observatory scientists. In short, the software creates additional value from existing data by leveraging the observatory's entire intellectual capacity. It enables rapid access to different data streams, and allows anyone to compare these data on a common time scale or map base. It frees discipline specialists from routine tasks like preparing graphics or compiling data tables, thereby making more time for interpretive efforts. It helps observatory scientists browse through data, and streamlines routine checks for unusual activity. It encourages a multi-parametric approach to volcano monitoring. And, by means of its own usefulness, it creates incentive to organize and capture data streams not yet available. Valve and Swarm are both written in Java, open-source, and freely available. Swarm is a stand-alone Java application. Valve is a system consisting of three parts: a web-based user interface, a graphing and analysis engine, and a data server. Both can be used non-interactively (e.g., via scripts) to generate graphs or to dump raw data. Swarm has a simple, built-in alarm capability. Several alarm algorithms have been built around Valve. Both programs remain under active

  19. 2008 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Neal, Christina A.; McGimsey, Robert G.; Dixon, James P.; Cameron, Cheryl E.; Nuzhdaev, Anton A.; Chibisova, Marina

    2011-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, and volcanic unrest or suspected unrest at seven separate volcanic centers in Alaska during 2008. Significant explosive eruptions at Okmok and Kasatochi Volcanoes in July and August dominated Observatory operations in the summer and autumn. AVO maintained 24-hour staffing at the Anchorage facility from July 12 through August 28. Minor eruptive activity continued at Veniaminof and Cleveland Volcanoes. Observed volcanic unrest at Cook Inlet's Redoubt Volcano presaged a significant eruption in the spring of 2009. AVO staff also participated in hazard communication regarding eruptions or unrest at nine volcanoes in Russia as part of a collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  20. 2009 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    McGimsey, Robert G.; Neal, Christina A.; Girina, Olga A.; Chibisova, Marina; Rybin, Alexander

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, and reports of unusual activity at or near eight separate volcanic centers in Alaska during 2009. The year was highlighted by the eruption of Redoubt Volcano, one of three active volcanoes on the western side of Cook Inlet and near south-central Alaska's population and commerce centers, which comprise about 62 percent of the State's population of 710,213 (2010 census). AVO staff also participated in hazard communication and monitoring of multiple eruptions at ten volcanoes in Russia as part of its collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  1. One hundred volatile years of volcanic gas studies at the Hawaiian Volcano Observatory: Chapter 7 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Sutton, A.J.; Elias, Tamar; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    The first volcanic gas studies in Hawai‘i, beginning in 1912, established that volatile emissions from Kīlauea Volcano contained mostly water vapor, in addition to carbon dioxide and sulfur dioxide. This straightforward discovery overturned a popular volatile theory of the day and, in the same action, helped affirm Thomas A. Jaggar, Jr.’s, vision of the Hawaiian Volcano Observatory (HVO) as a preeminent place to study volcanic processes. Decades later, the environmental movement produced a watershed of quantitative analytical tools that, after being tested at Kīlauea, became part of the regular monitoring effort at HVO. The resulting volatile emission and fumarole chemistry datasets are some of the most extensive on the planet. These data indicate that magma from the mantle enters the shallow magmatic system of Kīlauea sufficiently oversaturated in CO2 to produce turbulent flow. Passive degassing at Kīlauea’s summit that occurred from 1983 through 2007 yielded CO2-depleted, but SO2- and H2O-rich, rift eruptive gases. Beginning with the 2008 summit eruption, magma reaching the East Rift Zone eruption site became depleted of much of its volatile content at the summit eruptive vent before transport to Pu‘u ‘Ō‘ō. The volatile emissions of Hawaiian volcanoes are halogen-poor, relative to those of other basaltic systems. Information gained regarding intrinsic gas solubilities at Kīlauea and Mauna Loa, as well as the pressure-controlled nature of gas release, have provided useful tools for tracking eruptive activity. Regular CO2-emission-rate measurements at Kīlauea’s summit, together with surface-deformation and other data, detected an increase in deep magma supply more than a year before a corresponding surge in effusive activity. Correspondingly, HVO routinely uses SO2 emissions to study shallow eruptive processes and effusion rates. HVO gas studies and Kīlauea’s long-running East Rift Zone eruption also demonstrate that volatile emissions can

  2. The evolution of seismic monitoring systems at the Hawaiian Volcano Observatory: Chapter 2 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Okubo, Paul G.; Nakata, Jennifer S.; Koyanagi, Robert Y.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    In the century since the Hawaiian Volcano Observatory (HVO) put its first seismographs into operation at the edge of Kīlauea Volcano’s summit caldera, seismic monitoring at HVO (now administered by the U.S. Geological Survey [USGS]) has evolved considerably. The HVO seismic network extends across the entire Island of Hawai‘i and is complemented by stations installed and operated by monitoring partners in both the USGS and the National Oceanic and Atmospheric Administration. The seismic data stream that is available to HVO for its monitoring of volcanic and seismic activity in Hawai‘i, therefore, is built from hundreds of data channels from a diverse collection of instruments that can accurately record the ground motions of earthquakes ranging in magnitude from <1 to ≥8. In this chapter we describe the growth of HVO’s seismic monitoring systems throughout its first hundred years of operation. Although other references provide specific details of the changes in instrumentation and data handling over time, we recount here, in more general terms, the evolution of HVO’s seismic network. We focus not only on equipment but also on interpretative products and results that were enabled by the new instrumentation and by improvements in HVO’s seismic monitoring, analytical, and interpretative capabilities implemented during the past century. As HVO enters its next hundred years of seismological studies, it is well situated to further improve upon insights into seismic and volcanic processes by using contemporary seismological tools.

  3. Observatories

    CERN Document Server

    Krisciunas, K

    1999-01-01

    I give a brief history of astronomical observatories as an institution. This includes: 1) observatories in Islam; 2) China and India; 3) early European observatories; 4) the rise of national observatories; 5) private (amateur) observatories; 6) mountaintop observatories and the modern era. Additional references, to material not cited in the version that will be published in the encyclopedia, are also given.

  4. Implementation of Simple and Functional Web Applications at the Alaska Volcano Observatory Remote Sensing Group

    Science.gov (United States)

    Skoog, R. A.

    2007-12-01

    Web pages are ubiquitous and accessible, but when compared to stand-alone applications they are limited in capability. The Alaska Volcano Observatory (AVO) Remote Sensing Group has implemented web pages and supporting server software that provide relatively advanced features to any user able to meet basic requirements. Anyone in the world with access to a modern web browser (such as Mozilla Firefox 1.5 or Internet Explorer 6) and reasonable internet connection can fully use the tools, with no software installation or configuration. This allows faculty, staff and students at AVO to perform many aspects of volcano monitoring from home or the road as easily as from the office. Additionally, AVO collaborators such as the National Weather Service and the Anchorage Volcanic Ash Advisory Center are able to use these web tools to quickly assess volcanic events. Capabilities of this web software include (1) ability to obtain accurate measured remote sensing data values on an semi- quantitative compressed image of a large area, (2) to view any data from a wide time range of data swaths, (3) to view many different satellite remote sensing spectral bands and combinations, to adjust color range thresholds, (4) and to export to KML files which are viewable virtual globes such as Google Earth. The technologies behind this implementation are primarily Javascript, PHP, and MySQL which are free to use and well documented, in addition to Terascan, a commercial software package used to extract data from level-0 data files. These technologies will be presented in conjunction with the techniques used to combine them into the final product used by AVO and its collaborators for operational volcanic monitoring.

  5. The story of the Hawaiian Volcano Observatory -- A remarkable first 100 years of tracking eruptions and earthquakes

    Science.gov (United States)

    Babb, Janet L.; Kauahikaua, James P.; Tilling, Robert I.

    2011-01-01

    The year 2012 marks the centennial of the Hawaiian Volcano Observatory (HVO). With the support and cooperation of visionaries, financiers, scientists, and other individuals and organizations, HVO has successfully achieved 100 years of continuous monitoring of Hawaiian volcanoes. As we celebrate this milestone anniversary, we express our sincere mahalo—thanks—to the people who have contributed to and participated in HVO’s mission during this past century. First and foremost, we owe a debt of gratitude to the late Thomas A. Jaggar, Jr., the geologist whose vision and efforts led to the founding of HVO. We also acknowledge the pioneering contributions of the late Frank A. Perret, who began the continuous monitoring of Kīlauea in 1911, setting the stage for Jaggar, who took over the work in 1912. Initial support for HVO was provided by the Massachusetts Institute of Technology (MIT) and the Carnegie Geophysical Laboratory, which financed the initial cache of volcano monitoring instruments and Perret’s work in 1911. The Hawaiian Volcano Research Association, a group of Honolulu businessmen organized by Lorrin A. Thurston, also provided essential funding for HVO’s daily operations starting in mid-1912 and continuing for several decades. Since HVO’s beginning, the University of Hawaiʻi (UH), called the College of Hawaii until 1920, has been an advocate of HVO’s scientific studies. We have benefited from collaborations with UH scientists at both the Hilo and Mänoa campuses and look forward to future cooperative efforts to better understand how Hawaiian volcanoes work. The U.S. Geological Survey (USGS) has operated HVO continuously since 1947. Before then, HVO was under the administration of various Federal agencies—the U.S. Weather Bureau, at the time part of the Department of Agriculture, from 1919 to 1924; the USGS, which first managed HVO from 1924 to 1935; and the National Park Service from 1935 to 1947. For 76 of its first 100 years, HVO has been

  6. Volcano crisis response at Yellowstone volcanic complex - after-action report for exercise held at Salt Lake City, Utah, November 15, 2011

    Science.gov (United States)

    Pierson, Thomas C.; Driedger, Carolyn L.; Tilling, Robert I.

    2013-01-01

    A functional tabletop exercise was run on November 14-15, 2011 in Salt Lake City, Utah, to test crisis response capabilities, communication protocols, and decision-making by the staff of the multi-agency Yellowstone Volcano Observatory (YVO) as they reacted to a hypothetical exercise scenario of accelerating volcanic unrest at the Yellowstone caldera. The exercise simulated a rapid build-up of seismic activity, ground deformation, and hot-spring water-chemistry and temperature anomalies that culminated in a small- to moderate-size phreatomagmatic eruption within Yellowstone National Park. The YVO scientific team's responses to the unfolding events in the scenario and to simulated requests for information by stakeholders and the media were assessed by (a) the exercise organizers; (b) several non-YVO scientists, who observed and queried participants, and took notes throughout the exercise; and (c) the participants themselves, who kept logs of their actions during the exercise and later participated in a group debriefing session and filled out detailed questionnaires. These evaluations were tabulated, interpreted, and summarized for this report, and on the basis of this information, recommendations have been made. Overall, the YVO teams performed their jobs very well. The exercise revealed that YVO scientists were able to successfully provide critical hazards information, issue information statements, and appropriately raise alert levels during a fast-moving crisis. Based on the exercise, it is recommended that several measures be taken to increase YVO effectiveness during a crisis: 1. Improve role clarification within and between YVO science teams. 2. Improve communications tools and protocols for data-sharing and consensus-building among YVO scientists, who are geographically and administratively dispersed among various institutions across the United States. 3. Familiarize YVO staff with Incident Command System (ICS) procedures and protocols, and provide more in

  7. Volcanoes

    Science.gov (United States)

    ... or more from a volcano. Before a Volcanic Eruption The following are things you can do to ... in case of an emergency. During a Volcanic Eruption Follow the evacuation order issued by authorities and ...

  8. Volcanoes

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the past thousand years,volcanoes have claimed more than 300,000 lives. Volcanology is ayoung and dangerous science that helps us against the power of the Earth itself.We live on a fiery planet. Nearly 2000 miles beneath our feet, the Earth's inner core reachestemperatures of 12,000 degrees Fahrenheit. Molten rock or magma, rises to the earth's surface. Acold, rigid crust fractured into some twenty plates. When magma breaks through crust it becomes

  9. Volcanoes: Nature's Caldrons Challenge Geochemists.

    Science.gov (United States)

    Zurer, Pamela S.

    1984-01-01

    Reviews various topics and research studies on the geology of volcanoes. Areas examined include volcanoes and weather, plate margins, origins of magma, magma evolution, United States Geological Survey (USGS) volcano hazards program, USGS volcano observatories, volcanic gases, potassium-argon dating activities, and volcano monitoring strategies.…

  10. Lattice effects in YVO3 single crystal

    NARCIS (Netherlands)

    Marquina, C; Sikora, M; Ibarra, MR; Nugroho, AA; Palstra, TTM

    2005-01-01

    In this paper we report on the lattice effects in the Mott insulator yttrium orthovanadate (YVO3). Linear thermal expansion and magnetostriction experiments have been performed on a single crystal, in the temperature range from 5 K to room temperature. The YVO3 orders antiferromagnetically at T-N =

  11. A space-borne, multi-parameter, Virtual Volcano Observatory for the real-time, anywhere-anytime support to decision-making during eruptive crises

    Science.gov (United States)

    Ferrucci, F.; Tampellini, M.; Loughlin, S. C.; Tait, S.; Theys, N.; Valks, P.; Hirn, B.

    2013-12-01

    The EVOSS consortium of academic, industrial and institutional partners in Europe and Africa, has created a satellite-based volcano observatory, designed to support crisis management within the Global Monitoring for Environment and Security (GMES) framework of the European Commission. Data from 8 different payloads orbiting on 14 satellite platforms (SEVIRI on-board MSG-1, -2 and -3, MODIS on-board Terra and Aqua, GOME-2 and IASI onboard MetOp-A, OMI on-board Aura, Cosmo-SkyMED/1, /2, /3 and /4, JAMI on-board MTSAT-1 and -2, and, until April 8th2012, SCHIAMACHY on-board ENVISAT) acquired at 5 different down-link stations, are disseminated to and automatically processed at 6 locations in 4 countries. The results are sent, in four separate geographic data streams (high-temperature thermal anomalies, volcanic Sulfur dioxide daily fluxes, volcanic ash and ground deformation), to a central facility called VVO, the 'Virtual Volcano Observatory'. This system operates 24H/24-7D/7 since September 2011 on all volcanoes in Europe, Africa, the Lesser Antilles, and the oceans around them, and during this interval has detected, measured and monitored all subaerial eruptions occurred in this region (44 over 45 certified, with overall detection and processing efficiency of ~97%). EVOSS borne realtime information is delivered to a group of 14 qualified end users, bearing the direct or indirect responsibility of monitoring and managing volcano emergencies, and of advising governments in Comoros, DR Congo, Djibouti, Ethiopia, Montserrat, Uganda, Tanzania, France and Iceland. We present the full set of eruptions detected and monitored - from 2004 to present - by multispectral payloads SEVIRI onboard the geostationary platforms of the MSG constellation, for developing and fine tuning-up the EVOSS system along with its real-time, pre- and post-processing automated algorithms. The set includes 91% of subaerial eruptions occurred at 15 volcanoes (Piton de la Fournaise, Karthala, Jebel al

  12. Theoretical analysis and experimental research on thermal focal length of a YVO4/Nd:YVO4 composite crystal

    Institute of Scientific and Technical Information of China (English)

    Zhou Cheng

    2009-01-01

    This paper investigates the temperature field distribution and thermal focal length within a laser diode array(LDA)end-pumped YVO4/Nd:YVO4 rectangular composite crystal.A general expression of the temperature field distribution within the Nd:YVO4 rectangular crystal was obtained by analysing the characteristics of the Nd:YVO4 crystal and solving the Poisson equation with boundary conditions.The temperature field distributions in the Nd:YVO4 rectangular crystal for the YVO4/Nd:YVO4 composite crystal and the Nd:YVO4 single crystal are researched respectively.Calculating the thermal focal length within the Nd:YVO4 rectangular crystal was done by an analysis of the additional optical path differences(OPD)caused by heat,which was very identical with experimental results in this paper.Research results show that the maximum relative temperature on the rear face of the Nd:YVO4 crystal in the composite crystal is 150 K and the thermal focal length is 35.7 mm when the output power of the LDA is 22 W.In the same circumstances,the experimental value of the thermal focal length is 37.4 mm.So the relative error between the theoretical analysis and the experimental result is only 4.5%.With the same conditions,the thermal focal length of the Nd:YVO4 single crystal is 18.5 mm.So the relative rate of the thermal focal length between the YVO4/Nd:YVO4 crystal and the Nd:YVO4 crystal is 93%.So,the thermal stability of the output power and the beam quality of the YVO4/Nd:YVO4 laser is more advantageous than the laser with Nd:YVO4 single crystal.

  13. Elementary analysis of data from Tianchi Volcano

    Institute of Scientific and Technical Information of China (English)

    LIU Guo-ming; ZHANG Heng-rong; KONG Qing-jun; WU Cheng-zhi; GUO Feng; ZHANG Chao-fan

    2004-01-01

    Tianchi Volcano is the largest potential erupticve volcano in China. Analyzing these data on seismic monitoring, deformation observation and water chemistry investigation gained from the Tianchi Volcano Observatory (TVO), the authors consider that the Tianchi Volcano is in going into a new flourishing time.

  14. Volcano Preparedness

    Science.gov (United States)

    ... You might feel better to learn that an ‘active’ volcano is one that has erupted in the past ... miles away. If you live near a known volcano, active or dormant, following these tips will help you ...

  15. Effect of Photonic Structure on Optical Properties of YVO4:Eu3+ Phosphor

    Science.gov (United States)

    Thakur, Shashi; Dhiman, Naresh; Sharma, Amit; Gathania, Arvind K.

    2016-11-01

    Polymethyl methacrylate (PMMA) photonic crystal has been prepared on quartz substrate by the self-assembly vertical deposition technique. YVO4:Eu3+ inverse opal was obtained by annealing PMMA photonic crystal infiltrated with YVO4:Eu3+ nanophosphors at 500°C for 3 h. Scanning electron microscopy confirmed the development of the photonic and inverse opal structures. Photoluminescence study showed that the luminescence characteristics depended on the position of the photonic stop band. It was observed that the photoluminescence intensity of YVO4:Eu3+ inverse opal was enhanced near the photonic stop bandgap edge as compared with the intensity of a YVO4:Eu3+ nanophosphor powder sample.

  16. An overview of the Icelandic Volcano Observatory response to the on-going rifting event at Bárðarbunga (Iceland) and the SO2 emergency associated with the gas-rich eruption in Holuhraun

    Science.gov (United States)

    Barsotti, Sara; Jonsdottir, Kristin; Roberts, Matthew J.; Pfeffer, Melissa A.; Ófeigsson, Benedikt G.; Vögfjord, Kristin; Stefánsdóttir, Gerður; Jónasdóttir, Elin B.

    2015-04-01

    On 16 August, 2014, Bárðarbunga volcano entered a new phase of unrest. Elevated seismicity in the area with up to thousands of earthquakes detected per day and significant deformation was observed around the Bárðarbunga caldera. A dike intrusion was monitored for almost two weeks until a small, short-lived effusive eruption began on 29 August in Holuhraun. Two days later a second, more intense, tremendously gas-rich eruption started that is still (as of writing) ongoing. The Icelandic Volcano Observatory (IVO), within the Icelandic Meteorological Office (IMO), monitors all the volcanoes in Iceland. Responsibilities include evaluating their related hazards, issuing warnings to the public and Civil Protection, and providing information regarding risks to aviation, including a weekly summary of volcanic activity provided to the Volcanic Ash Advisory Center in London. IVO has monitored the Bárðarbunga unrest phase since its beginning with the support of international colleagues and, in collaboration with the University of Iceland and the Environment Agency of Iceland, provides scientific support and interpretation of the ongoing phenomena to the local Civil Protection. The Aviation Color Code, for preventing hazards to aviation due to ash-cloud encounter, has been widely used and changed as soon as new observations and geophysical data from the monitoring network have suggested a potential evolution in the volcanic crisis. Since the onset of the eruption, IVO is monitoring the gas emission by using different and complementary instrumentations aimed at analyzing the plume composition as well as estimating the gaseous fluxes. SO2 rates have been measured with both real-time scanning DOASes and occasional mobile DOAS traveses, near the eruption site and in the far field. During the first month-and-a-half of the eruption, an average flux equal to 400 kg/s was registered, with peaks exceeding 1,000 kg/s. Along with these measurements the dispersal model CALPUFF has

  17. Magnetic Behavior of a Mott-Insulator YVO3

    Science.gov (United States)

    Kawano, Hazuki; Yoshizawa, Hideki; Ueda, Yutaka

    1994-08-01

    As one of the members of the ABO3-type pseudoperovskite oxide family, Y1-xCaxVO3 exhibits an insulator-metal transition upon a change in the dopant calcium ion concentration x. We have reinvestigated the magnetic structure of the parent compound YVO3 with use of the neutron scattering technique. YVO3 orders at T N1=118 K with the so-called C-type antiferromagnetic structure, but changes to the G-type antiferromagnetic structure at T N2˜77 K through a first order transition with lattice distortion. These spin structures differ from those of an early study by Zubkov et al. (Sov. Phys.-JETP 39 (1974) 896). The static moment which contributes to the magnetic long range order is extrapolated to be less than 1.6 µ B at T=0 K. This value of the static moment is more than 20% smaller than 2.0 µ B expected for a localized spin system with S=1, indicating the existence of spin fluctuations in a Mott insulator YVO3.

  18. Vanishing Volcano

    Institute of Scientific and Technical Information of China (English)

    杨树仁

    1995-01-01

    Mauna Loa, the world’s largest active volcano,is sinking into the Pacific Ocean——and it’s taking the main island of Hawaii with it! The problem:The mighty volcano has gained too much weight, says Peter Lipman of the U. S. Geological Survey.

  19. USGS Volcano Observatory Notices for Aviation (VONA)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Website provides succinct, plain-English messages aimed at dispatchers, pilots, and air traffic controllers to inform them of volcanic unrest and eruptive activity...

  20. Catalogue of Icelandic Volcanoes

    Science.gov (United States)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Gudmundsson, Magnus T.; Vogfjord, Kristin; Pagneux, Emmanuel; Oddsson, Bjorn; Barsotti, Sara; Karlsdottir, Sigrun

    2016-04-01

    The Catalogue of Icelandic Volcanoes is a newly developed open-access web resource in English intended to serve as an official source of information about active volcanoes in Iceland and their characteristics. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland GOSVÁ (commenced in 2012), as well as being part of the effort of FUTUREVOLC (2012-2016) on establishing an Icelandic volcano supersite. Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene (the time since the end of the last glaciation - approximately the last 11,500 years). In the last 50 years, over 20 eruptions have occurred in Iceland displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and the distribution lava and tephra. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in numerous scientific papers and other publications. In 2010, the International Civil Aviation Organisation (ICAO) funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU through the FP7 project FUTUREVOLC. The Catalogue of Icelandic Volcanoes is a collaboration of the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Civil Protection Department of the National Commissioner of the Iceland Police, with contributions from a large number of specialists in Iceland and elsewhere. The Catalogue is built up of chapters with texts and various

  1. Dante's volcano

    Science.gov (United States)

    1994-09-01

    This video contains two segments: one a 0:01:50 spot and the other a 0:08:21 feature. Dante 2, an eight-legged walking machine, is shown during field trials as it explores the inner depths of an active volcano at Mount Spurr, Alaska. A NASA sponsored team at Carnegie Mellon University built Dante to withstand earth's harshest conditions, to deliver a science payload to the interior of a volcano, and to report on its journey to the floor of a volcano. Remotely controlled from 80-miles away, the robot explored the inner depths of the volcano and information from onboard video cameras and sensors was relayed via satellite to scientists in Anchorage. There, using a computer generated image, controllers tracked the robot's movement. Ultimately the robot team hopes to apply the technology to future planetary missions.

  2. Fluorescence dynamics of YVO{sub 4}:Tm{sup 3+}, YVO{sub 4}:Tm{sup 3+}, Tb{sup 3+} and YVO{sub 4}:Tm{sup 3+}, Ho{sup 3+} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Bettinelli, M. [Dipartimento Scientifico e Tecnologico, Universite di Verona, Ca' Vignal, Strada Le Grazie, 37134 Verona (Italy); Ermeneux, F.S.; Moncorge, R. [Laboratoire de Physico-Chimie des Materiaux Luminescents, UMR 5620 CNRS, Universite Claude Bernard Lyon I, 43, boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); Cavalli, E. [Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica e Chimica Fisica, Universita di Parma, Viale delle Scienze, 43100 Parma (Italy)

    1998-09-21

    The fluorescence dynamics of the {sup 3}H{sub 4} and {sup 3}F{sub 4} energy levels of Tm{sup 3+} in YVO{sub 4} single crystals codoped or not codoped with Tb{sup 3+} and Ho{sup 3+} ions was experimentally investigated and compared with classical energy-transfer models. In the YVO{sub 4}:1% Tm{sup 3+} and YVO{sub 4}:1% Tm{sup 3+}, 1% Ho{sup 3+} crystals, the {sup 3}H{sub 4} state relaxes predominantly by internal cross-relaxation-type energy transfers, whereas in the YVO{sub 4}:0.5% Tm{sup 3+}, 1% Tb{sup 3+} and YVO{sub 4}:1% Tm{sup 3+}, 1% Tb{sup 3+} crystals the relaxation is dominated by direct energy transfers to the {sup 7}F{sub 1} state of the Tb{sup 3+} ions. In all of the codoped systems, strong energy transfers from the {sup 3}F{sub 4} state of the Tm{sup 3+} ions to the {sup 7}F{sub 1} and {sup 5}I{sub 7} states of the Tb{sup 3+} and Ho{sup 3+} codopants were evident. The electric dipole-electric dipole coupling parameter was evaluated for several cross-relaxation and direct-energy-transfer processes. (author)

  3. What Are Volcano Hazards?

    Science.gov (United States)

    ... Sheet 002-97 Revised March 2008 What Are Volcano Hazards? Volcanoes give rise to numerous geologic and ... as far as 15 miles from the volcano. Volcano Landslides A landslide or debris avalanche is a ...

  4. Catalogue of Icelandic volcanoes

    Science.gov (United States)

    Ilyinskaya, Evgenia; Larsen, Gudrun; Vogfjörd, Kristin; Tumi Gudmundsson, Magnus; Jonsson, Trausti; Oddsson, Björn; Reynisson, Vidir; Barsotti, Sara; Karlsdottir, Sigrun

    2015-04-01

    Volcanic activity in Iceland occurs on volcanic systems that usually comprise a central volcano and fissure swarm. Over 30 systems have been active during the Holocene. In the last 100 years, over 30 eruptions have occurred displaying very varied activity in terms of eruption styles, eruptive environments, eruptive products and their distribution. Although basaltic eruptions are most common, the majority of eruptions are explosive, not the least due to magma-water interaction in ice-covered volcanoes. Extensive research has taken place on Icelandic volcanism, and the results reported in scientific papers and other publications. In 2010, the International Civil Aviation Organisation funded a 3 year project to collate the current state of knowledge and create a comprehensive catalogue readily available to decision makers, stakeholders and the general public. The work on the Catalogue began in 2011, and was then further supported by the Icelandic government and the EU. The Catalogue forms a part of an integrated volcanic risk assessment project in Iceland (commenced in 2012), and the EU FP7 project FUTUREVOLC (2012-2016), establishing an Icelandic volcano Supersite. The Catalogue is a collaborative effort between the Icelandic Meteorological Office (the state volcano observatory), the Institute of Earth Sciences at the University of Iceland, and the Icelandic Civil Protection, with contributions from a large number of specialists in Iceland and elsewhere. The catalogue is scheduled for opening in the first half of 2015 and once completed, it will be an official publication intended to serve as an accurate and up to date source of information about active volcanoes in Iceland and their characteristics. The Catalogue is an open web resource in English and is composed of individual chapters on each of the volcanic systems. The chapters include information on the geology and structure of the volcano; the eruption history, pattern and products; the known precursory signals

  5. Synthesis of YVO4:Eu3+/YBO3Heteronanostructures with Enhanced Photoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Hu Haihua

    2009-01-01

    Full Text Available Abstract Novel YVO4:Eu3+/YBO3core/shell heteronanostructures with different shell ratios (SRs were successfully prepared by a facile two-step method. X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize the heteronanostructures. Photoluminescence (PL study reveals that PL efficiency of the YVO4:Eu3+nanocrystals (cores can be improved by the growth of YBO3nanocoatings onto the cores to form the YVO4:Eu3+/YBO3core/shell heteronanostructures. Furthermore, shell ratio plays a critical role in their PL efficiency. The heteronanostructures (SR = 1/7 exhibit the highest PL efficiency; its PL intensity of the5D0–7F2emission at 620 nm is 27% higher than that of the YVO4:Eu3+nanocrystals under the same conditions.

  6. Functionalization of luminescent YVO{sub 4}:Eu{sup 3+} nanoparticles by sol–gel

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Barbara A.; Ferreira, Natália H.; Oliveira, Pollyanna F.; Faria, Emerson H. de; Tavares, Denise C.; Rocha, Lucas A.; Ciuffi, Katia J.; Nassar, Eduardo J., E-mail: eduardo.nassar@unifran.edu.br

    2015-03-15

    Over the last decades, researchers have explored nanotechnological applications in different areas. The non-hydrolytic and hydrolytic sol–gel routes offer the ideal conditions to obtain materials with distinct compositions and multifunctionality, for use in such diverse areas as nanomedicine and technology. In this work, we used the modified hydrolytic sol–gel route to prepare YVO{sub 4} doped with Eu{sup 3+} ion. The YVO{sub 4}:Eu{sup 3+} nanoparticles were functionalized with 3-chloropropyltriethoxysilane using the hydrolytic sol–gel process; the drug cisplatin was then added to them. The final powder was characterized by thermal analysis, infrared spectroscopy, X-ray diffraction, and photoluminescence. The powder X-ray diffraction patterns of the samples obtained before and after functionalization revealed well defined peaks ascribed to the tetragonal structure of the YVO{sub 4} phase. The thermal analysis curves evidenced mass loss relative to 3-chloropropyltriethoxysilane and cisplatin decomposition. Infrared spectroscopy showed the peaks related to the CH and NH groups vibration modes, confirming YVO{sub 4} functionalization. The excitation and emission spectrum of the Eu{sup 3+} ion did not change upon its doping into the matrix functionalized with 3-chloropropyl and cisplatin. Cytotoxicity tests conducted on normal Chinese hamster (V79 cells) and murine melanoma (B16F10) cells attested that the matrix was not toxic. - Highlights: • Sol–gel methodology was used to obtain luminescent YVO{sub 4}. • Matrix was functionalized by alkoxide. • YVO{sub 4} matrix was not toxic. • YVO{sub 4}:Eu{sup 3+} nanoparticles existed in the cell cytoplasm and nucleus. • YVO{sub 4}:Eu{sup 3+} can function as a fluorescent label and drug delivery system.

  7. Taosi Observatory

    Science.gov (United States)

    Sun, Xiaochun

    Taosi observatory is the remains of a structure discovered at the later Neolithic Taosi site located in Xiangfen County, Shanxi Province, in north-central China. The structure is a walled enclosure on a raised platform. Only rammed-earth foundations of the structure remained. Archaeoastronomical studies suggest that this structure functioned as an astronomical observatory. Historical circumstantial evidence suggests that it was probably related to the legendary kingdom of Yao from the twenty-first century BC.

  8. Comparing the luminescence processes of YVO{sub 4}:Eu and core-shell YVO{sub 4}@YF{sub 3} nanocrystals with bulk-YVO{sub 4}:Eu

    Energy Technology Data Exchange (ETDEWEB)

    Shirmane, L., E-mail: liana.shirmane@gmail.com [Institute of Solid State Physics, University of Latvia, 8 Kengaraga iela, LV-1063 Riga (Latvia); Feldmann, C. [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstrasse 15, D-76131 Karlsruhe (Germany); Pankratov, V., E-mail: vladimirs.pankratovs@oulu.fi [Institute of Solid State Physics, University of Latvia, 8 Kengaraga iela, LV-1063 Riga (Latvia); MAX IV Laboratory, Box 118, S-221 00 Lund (Sweden); Research Center of Molecular Materials, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland)

    2017-01-01

    Comparative analysis of bulk, non-coated and core-shelled nanocrystalline YVO{sub 4}:Eu was performed by means of time-resolved luminescence and VUV excitation luminescence spectroscopy techniques. Nanocrystalline YVO{sub 4}:Eu samples – both as-prepared and YF{sub 3} core-shelled – have been synthesized by means of a microwave-assisted synthesis in ionic liquids, which allows to obtain 10–12 nm nanoparticles with high crystallinity. The results show noticeable differences between bulk and nanocrystalline YVO{sub 4}:Eu in photoluminescence experimental data, which explains by influence of the nanocrystal surface. A YF{sub 3} core-shell layer around YVO{sub 4}:Eu nanoparticles partially recovers the intensity of the Eu{sup 3+} emission. It is demonstrated that the Eu{sup 3+} luminescence recovery is achieved at the expense of the suppression of the intrinsic emission but not due to the passivation of surface loss centers in core-shelled nanocrystals. It is also shown that surface loss processes are the reason of the degradation of energy transfer efficiency from the host lattice to Eu{sup 3+} under high-energy excitations in vacuum ultraviolet spectral range.

  9. Instrumentation Recommendations for Volcano Monitoring at U.S. Volcanoes Under the National Volcano Early Warning System

    Science.gov (United States)

    Moran, Seth C.; Freymueller, Jeff T.; LaHusen, Richard G.; McGee, Kenneth A.; Poland, Michael P.; Power, John A.; Schmidt, David A.; Schneider, David J.; Stephens, George; Werner, Cynthia A.; White, Randall A.

    2008-01-01

    As magma moves toward the surface, it interacts with anything in its path: hydrothermal systems, cooling magma bodies from previous eruptions, and (or) the surrounding 'country rock'. Magma also undergoes significant changes in its physical properties as pressure and temperature conditions change along its path. These interactions and changes lead to a range of geophysical and geochemical phenomena. The goal of volcano monitoring is to detect and correctly interpret such phenomena in order to provide early and accurate warnings of impending eruptions. Given the well-documented hazards posed by volcanoes to both ground-based populations (for example, Blong, 1984; Scott, 1989) and aviation (for example, Neal and others, 1997; Miller and Casadevall, 2000), volcano monitoring is critical for public safety and hazard mitigation. Only with adequate monitoring systems in place can volcano observatories provide accurate and timely forecasts and alerts of possible eruptive activity. At most U.S. volcanoes, observatories traditionally have employed a two-component approach to volcano monitoring: (1) install instrumentation sufficient to detect unrest at volcanic systems likely to erupt in the not-too-distant future; and (2) once unrest is detected, install any instrumentation needed for eruption prediction and monitoring. This reactive approach is problematic, however, for two reasons. 1. At many volcanoes, rapid installation of new ground-1. based instruments is difficult or impossible. Factors that complicate rapid response include (a) eruptions that are preceded by short (hours to days) precursory sequences of geophysical and (or) geochemical activity, as occurred at Mount Redoubt (Alaska) in 1989 (24 hours), Anatahan (Mariana Islands) in 2003 (6 hours), and Mount St. Helens (Washington) in 1980 and 2004 (7 and 8 days, respectively); (b) inclement weather conditions, which may prohibit installation of new equipment for days, weeks, or even months, particularly at

  10. Santorini Volcano

    Science.gov (United States)

    Druitt, T.H.; Edwards, L.; Mellors, R.M.; Pyle, D.M.; Sparks, R.S.J.; Lanphere, M.; Davies, M.; Barreirio, B.

    1999-01-01

    Santorini is one of the most spectacular caldera volcanoes in the world. It has been the focus of significant scientific and scholastic interest because of the great Bronze Age explosive eruption that buried the Minoan town of Akrotiri. Santorini is still active. It has been dormant since 1950, but there have been several substantial historic eruptions. Because of this potential risk to life, both for the indigenous population and for the large number of tourists who visit it, Santorini has been designated one of five European Laboratory Volcanoes by the European Commission. Santorini has long fascinated geologists, with some important early work on volcanoes being conducted there. Since 1980, research groups at Cambridge University, and later at the University of Bristol and Blaise Pascal University in Clermont-Ferrand, have collected a large amount of data on the stratigraphy, geochemistry, geochronology and petrology of the volcanics. The volcanic field has been remapped at a scale of 1:10 000. A remarkable picture of cyclic volcanic activity and magmatic evolution has emerged from this work. Much of this work has remained unpublished until now. This Memoir synthesizes for the first time all the data from the Cambridge/Bristol/Clermont groups, and integrates published data from other research groups. It provides the latest interpretation of the tectonic and magmatic evolution of Santorini. It is accompanied by the new 1:10 000 full-colour geological map of the island.

  11. Optical Spectroscopy and Visible Upconversion Studies of YVO4:Er3+ Nanocrystals Synthesized by a Hydrothermal Process

    NARCIS (Netherlands)

    Sun, Y.; Liu, H.; Wang, X.; Kong, X.; Zhang, H.

    2006-01-01

    Abstract: Strong visible emissions of Er3+ resulting from two-photon absorption and energy transfer from the host YVO4 were observed in nanocrystalline Er3+-doped YVO4, which was prepared by a hydrothermal method using a citrate-yttrium-vanadate complex as the precursor. The nanocrystals were

  12. Optical Spectroscopy and Visible Upconversion Studies of YVO4:Er3+ Nanocrystals Synthesized by a Hydrothermal Process

    NARCIS (Netherlands)

    Sun, Y.; Liu, H.; Wang, X.; Kong, X.; Zhang, H.

    2006-01-01

    Abstract: Strong visible emissions of Er3+ resulting from two-photon absorption and energy transfer from the host YVO4 were observed in nanocrystalline Er3+-doped YVO4, which was prepared by a hydrothermal method using a citrate-yttrium-vanadate complex as the precursor. The nanocrystals were charac

  13. WOVOdat Progress 2012: Installable DB template for Volcano Monitoring Database

    Science.gov (United States)

    Ratdomopurbo, A.; Widiwijayanti, C.; Win, N.-T.-Z.; Chen, L.-D.; Newhall, C.

    2012-04-01

    WOVOdat is the World Organization of Volcano Observatories' (WOVO) Database of Volcanic Unrest. Volcanoes are frequently restless but only a fraction of unrest leads to eruptions. We aim to compile and make the data of historical volcanic unrest available as a reference tool during volcanic crises, for observatory or other user to compare or look for systematic in many unrest episodes, and also provide educational tools for teachers and students on understanding volcanic processes. Furthermore, we promote the use of relational databases for countries that are still planning to develop their own monitoring database. We are now in the process of populating WOVOdat in collaboration with volcano observatories worldwide. Proprietary data remains at the observatories where the data originally from. Therefore, users who wish to use the data for publication or to obtain detail information about the data should directly contact the observatories. To encourage the use of relational database system in volcano observatories with no monitoring database, WOVOdat project is preparing an installable standalone package. This package is freely downloadable through our website (www.wovodat.org), ready to install and serve as database system in the local domain to host various types of volcano monitoring data. The WOVOdat project is now hosted at Earth Observatory of Singapore (Nanyang Technological University). In the current stage of data population, our website supports interaction between WOVOdat developers, observatories, and other partners in building the database, e.g. accessing schematic design, information and documentation, and also data submission. As anticipation of various data formats coming from different observatories, we provide an interactive tools for user to convert their data into standard WOVOdat format file before then able to upload and store in the database system. We are also developing various visualization tools that will be integrated in the system to ease

  14. Operational characteristics of dual gain single cavity Nd:YVO4 laser

    Indian Academy of Sciences (India)

    Pranab K Mukhopadhyay; Jogy George; S K Sharma; P K Gupta; T P S Nathan

    2002-01-01

    Operational characteristics of a dual gain single cavity Nd:YVO4 laser have been investigated. With semiconductor diode laser pump power of 2 W, 800 mW output was obtained with a slope efficiency of 49%. Further, by changing the relative orientation of the two crystals the polarization characteristics of the output could be varied. In particular by keeping the two Nd:YVO4 crystals with their -axes orthogonal to each other and adjusting the gain of the crystals so that both operate at approximately the same power level, completely unpolarized beams could be obtained.

  15. First scientific contributions from the High Altitude Water Cherenkov Observatory

    Science.gov (United States)

    León Vargas, H.; HAWC Collaboration

    2015-09-01

    The High Altitude Water Cherenkov Observatory (HAWC), located at the slopes of the volcanoes Sierra Negra and Pico de Orizaba in Mexico, was inaugurated on March 20, 2015. However, data taking started in August 2013 with a partially deployed observatory and since then the instrument has collected data as it got closer to its final configuration. HAWC is a ground based TeV gamma-ray observatory with a large field of view that will be used to study the Northern sky with high sensitivity. In this contribution we present some of the results obtained with the partially built instrument and the expected capabilities to detect different phenomena with the complete observatory.

  16. Influence of Bi3+ ions on the excitation wavelength of the YVO4:Eu3+ matrix

    Science.gov (United States)

    Matos, Marcela G.; Rocha, Lucas A.; Nassar, Eduardo J.; Verelst, Marc

    2016-12-01

    This work used the non-hydrolytic sol-gel process to prepare co-activated Eu3+/Bi3+ in YVO4 phosphors. We employed X-ray diffraction, which confirmed a tetragonal structure, and photoluminescence to characterize the structure and investigate the photoluminescence properties of the YVO4:Eu3+,Bi3+ matrixes. The large band between 250 and 380 nm in the excitation spectrum of YVO4:Eu3+,Bi3+ corresponded to a ligand-metal charge transfer band (VO43- → Eu3+). Addition of Bi3+ ions increased the charge transfer band and intensified the emission of Eu3+ ions. The x and y color coordinates of the phosphors ranged from 0.60 to 0.68 and from 0.32 to 0.39, respectively. The emission spectrum displayed an intense red emission centered at 618.5 nm, due to the 5D0 → 7F2 transition of Eu3+. The optimal Bi3+ concentration in the phosphor was 1% in mol, which provided more intense emission and longer lifetime. The results indicated that YVO4:Eu3+,Bi3+ is a potential red phosphor with application as biological marker.

  17. A comparative Raman study between YbVO3 and YVO3

    NARCIS (Netherlands)

    Jandl, S.; Nugroho, A.A.; Palstra, T.T.M.

    2010-01-01

    An orbital ordering effect is observed in YbVO3 around 170 K while the crystal structure is orthorhombic (space group pnma). A monoclinic transition has been reported below TN = 104 K, while according to recent specific heat measurements, it occurs at 170 K. The crystal structure of YVO3 at 300 K is

  18. Renewed unrest at Mount Spurr Volcano, Alaska

    Science.gov (United States)

    Power, John A.

    2004-01-01

    The Alaska Volcano Observatory (AVO),a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys, has detected unrest at Mount Spurr volcano, located about 125 km west of Anchorage, Alaska, at the northeast end of the Aleutian volcanic arc.This activity consists of increased seismicity melting of the summit ice cap, and substantial rates of C02 and H2S emission.The current unrest is centered beneath the volcano's 3374-m-high summit, whose last known eruption was 5000–6000 years ago. Since then, Crater Peak, 2309 m in elevation and 4 km to the south, has been the active vent. Recent eruptions occurred in 1953 and 1992.

  19. Magma supply, storage, and transport at shield-stage Hawaiian volcanoes: Chapter 5 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Poland, Michael P.; Miklius, Asta; Montgomery-Brown, Emily K.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    The characteristics of magma supply, storage, and transport are among the most critical parameters governing volcanic activity, yet they remain largely unconstrained because all three processes are hidden beneath the surface. Hawaiian volcanoes, particularly Kīlauea and Mauna Loa, offer excellent prospects for studying subsurface magmatic processes, owing to their accessibility and frequent eruptive and intrusive activity. In addition, the Hawaiian Volcano Observatory, founded in 1912, maintains long records of geological, geophysical, and geochemical data. As a result, Hawaiian volcanoes have served as both a model for basaltic volcanism in general and a starting point for many studies of volcanic processes.

  20. Volcano Monitoring Using Google Earth

    Science.gov (United States)

    Bailey, J. E.; Dehn, J.; Webley, P.; Skoog, R.

    2006-12-01

    At the Alaska Volcano Observatory (AVO), Google Earth is being used as a visualization tool for operational satellite monitoring of the region's volcanoes. Through the abilities of the Keyhole Markup Language (KML) utilized by Google Earth, different datasets have been integrated into this virtual globe browser. Examples include the ability to browse thermal satellite image overlays with dynamic control, to look for signs of volcanic activity. Webcams can also be viewed interactively through the Google Earth interface to confirm current activity. Other applications include monitoring the location and status of instrumentation; near real-time plotting of earthquake hypocenters; mapping of new volcanic deposits; and animated models of ash plumes within Google Earth, created by a combination of ash dispersion modeling and 3D visualization packages. The globe also provides an ideal interface for displaying near real-time information on detected thermal anomalies or "hotspot"; pixels in satellite images with elevated brightness temperatures relative to the background temperature. The Geophysical Institute at the University of Alaska collects AVHRR (Advanced Very High Resolution Radiometer) and MODIS (Moderate Resolution Imaging Spectroradiometer) through its own receiving station. The automated processing that follows includes application of algorithms that search for hotspots close to volcano location, flagging those that meet certain criteria. Further automated routines generate folders of KML placemarkers, which are linked to Google Earth through the network link function. Downloadable KML files have been created to provide links to various data products for different volcanoes and past eruptions, and to demonstrate examples of the monitoring tools developed. These KML files will be made accessible through a new website that will become publicly available in December 2006.

  1. Global Volcano Locations Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC maintains a database of over 1,500 volcano locations obtained from the Smithsonian Institution Global Volcanism Program, Volcanoes of the World publication. The...

  2. A Scientific Excursion: Volcanoes.

    Science.gov (United States)

    Olds, Henry, Jr.

    1983-01-01

    Reviews an educationally valuable and reasonably well-designed simulation of volcanic activity in an imaginary land. VOLCANOES creates an excellent context for learning information about volcanoes and for developing skills and practicing methods needed to study behavior of volcanoes. (Author/JN)

  3. YVO4∶ Tm3+的真空紫外发光性能%Vacuum Ultraviolet Spectra of YVO4:Tm3 +

    Institute of Scientific and Technical Information of China (English)

    沈雷军; 李波; 王忠志; 高乐乐; 周永勃; 赵增祺; 张国斌

    2014-01-01

    通过高温固相反应合成 YVO4∶ xTm(x =0.001,0.003,0.005,0.007,0.01,0.03,0.05)蓝色系列粉末状发光材料。经 X 射线衍射分析产物为单相,属四方锆英石结构,其结果与 JCPDS 标准卡(72-0861)相符。检测了材料的真空紫外激发光谱和发射光谱。 YVO4∶ xTm 的真空紫外激发光谱在120~350 nm 范围内为连续的带状峰,在155 nm 和333 nm 附近有明显的峰值。在155 nm 激发下,YVO4∶ xTm 的发射光谱由两部分组成,其中主发射峰在474 nm 附近呈一尖锐的线状,来自 Tm3+的1 G4→3 H6跃迁;在650 nm 左右有一弱发射峰,来自Tm3+的1 G4→3 H4跃迁。另外,还有一较弱的带状发射,中心位于540 nm 左右,来自样品的 VO3-4离子的宽带发射。随着 Tm3+摩尔分数 x 由0.001增加到0.005,Tm3+发射光谱强度逐渐增加到最大值。之后随着 x 继续增加,发射光谱强度逐渐下降,呈现明显的浓度猝灭现象。通过对 YVO4∶ xTm 的光谱分析及其发光机理进行推导,认为 YVO4∶ Tm3+在紫外及真空紫外激发下,是一种具有较高发光效率以及色纯度较好的蓝色发光材料。%Series of blue phosphors YVO4∶ xTm (x = 0. 001, 0. 003, 0. 005, 0. 007, 0. 01, 0. 03, 0. 05) were synthesized by the high temperature solid state reaction in this paper. X-ray diffraction shows that the product is a tetragonal zircon structured single phase. The result is consistent with JCPDS standard card (72-0861). The vacuum UV excitation spectrum and emission spectra of the phosphors at room temperature were also detected. The vacuum UV excitation spectrum of YVO4 ∶xTm includes a continuous banded peak in the range of 120 - 350 nm, and there are two significant peaks at 155 nm and 333 nm. Excited by 155 nm, the emission spectrum of YVO4∶ xTm consists of two parts. The main emission spectrum at 474 nm is a sharp peak, caused by 1 G4→3 H6 transition of Tm3 + . The weaker emission peak is at 650 nm, which is generated by 1 G4

  4. Volcano seismology

    Science.gov (United States)

    Chouet, B.

    2003-01-01

    A fundamental goal of volcano seismology is to understand active magmatic systems, to characterize the configuration of such systems, and to determine the extent and evolution of source regions of magmatic energy. Such understanding is critical to our assessment of eruptive behavior and its hazardous impacts. With the emergence of portable broadband seismic instrumentation, availability of digital networks with wide dynamic range, and development of new powerful analysis techniques, rapid progress is being made toward a synthesis of high-quality seismic data to develop a coherent model of eruption mechanics. Examples of recent advances are: (1) high-resolution tomography to image subsurface volcanic structures at scales of a few hundred meters; (2) use of small-aperture seismic antennas to map the spatio-temporal properties of long-period (LP) seismicity; (3) moment tensor inversions of very-long-period (VLP) data to derive the source geometry and mass-transport budget of magmatic fluids; (4) spectral analyses of LP events to determine the acoustic properties of magmatic and associated hydrothermal fluids; and (5) experimental modeling of the source dynamics of volcanic tremor. These promising advances provide new insights into the mechanical properties of volcanic fluids and subvolcanic mass-transport dynamics. As new seismic methods refine our understanding of seismic sources, and geochemical methods better constrain mass balance and magma behavior, we face new challenges in elucidating the physico-chemical processes that cause volcanic unrest and its seismic and gas-discharge manifestations. Much work remains to be done toward a synthesis of seismological, geochemical, and petrological observations into an integrated model of volcanic behavior. Future important goals must include: (1) interpreting the key types of magma movement, degassing and boiling events that produce characteristic seismic phenomena; (2) characterizing multiphase fluids in subvolcanic

  5. The seismicity of Marapi volcano, West Sumatra.

    Science.gov (United States)

    D'Auria, L.

    2009-04-01

    Marapi is one of the active volcanoes in West Sumatra. It is a stratovolcano with an edifice that is elongated in the ENE-WSW direction. Its elevation is about 2,900 m a.s.l. The summit area is characterized by a caldera that contains some active craters aligned along the ENE-WSW direction. The Marapi volcano is an attractive region for tourists and hosts many small communities its surrounding areas. The recent history of Mt. Marapi is characterized by explosive activity at the summit craters. No lava flows have passed the rim of the summit caldera in recent times. The last eruption occurred on August 5, 2004, and consisted of moderate explosive activity from the central crater. In 1975 an eruption with magmatic and phreatic explosive phases and mudflows and lahars occurred that caused fatalities in the surrounding areas. Since 1980 other eruptions have occurred at Marapi volcano. Even if the explosive intensities of those eruptions have been small to moderate, in some cases, there were fatalities. A cooperation project started between Italy and Indonesia (COVIN) for the monitoring of volcanoes in West Sumatra. In the context of this project a monitoring centre has been set up at the Bukittinggi Observatory and a seismological monitoring system for Marapi volcano has been realized. This system is based on a broadband seismic network including 4 three-component stations. The data acquired by the broadband network of Marapi volcano are continuous recordings of the seismic signals starting from 19/10/2006. Volcano-Tectonic and Long Period events of Marapi volcano together with regional and teleseismic earthquakes are recorded. Several events of high magnitude located at short distances from the network were also recorded such as on March 6, 2007, when two events of Magnitudes Mw 6.4 and 6.3 were recorded with the epicentres near the Marapi volcano. During the following days, there was a sequence of hundreds of aftershocks. The preliminary analysis of the seismicity of

  6. Growth and characterization of self-Q-switched Nd:Cr:YVO4 crystal.

    Science.gov (United States)

    Pan, Z B; Yao, B; Yu, H H; Xu, H H; Wang, Z P; Wang, J Y; Zhang, H J

    2012-01-30

    A Nd:Cr:YVO4 crystal was grown by the Czochralski method for the first time to our knowledge. Its structure and cell parameter have been studied by X-ray powder diffraction (XRPD) analysis. Polarized absorption spectra were measured at room temperature, which showed that the absorption bands display polarization character and an absorption band of Cr5+ ions at 1110 nm enables the crystal to be a self-Q-switched laser material. We also found that the absorption of Cr5+ ions became much larger and its self-Q-switched laser performance became much better when the Nd:Cr:YVO4 crystal was annealed because the annealing induces more Cr ions to become those with + 5 valence. In the self-Q-switched laser, the maximum output power, shortest pulse width, and largest pulse energy were obtained to be 120 mW, 85.8 ns, and 0.79 μJ, respectively.

  7. Observation of the effective linear polarization induced by the asymmetrical Raman gain of YVO4 crystal

    Science.gov (United States)

    Zhuang, Fengjiang; Lin, Zhiyang; Zhu, Siqi

    2016-10-01

    We originally present a linearly polarized Raman radiation emitted from an actively Q-switched Nd:YAG/YVO4 laser. An 1175.25 nm Raman output was achieved using a uniaxial a-cut YVO4 crystal in a Z-shape laser cavity. The stable Raman power of 1.8 W was obtained, corresponding conversion efficiency of 8.8% from 1064 nm to 1175 nm. The Raman radiation with a polarization extinction ratio of 10.4-dB was observed for the first time. Our experimental results demonstrate that the asymmetrical Raman crystal gain can result in a uniform linear polarization and permit emitting orthogonal polarization radiation in a cascaded Raman laser.

  8. Molten salt synthesis and luminescent properties of YVO4:Eu nanocrystalline phosphors

    Institute of Scientific and Technical Information of China (English)

    WANG Fang; LIU Chenglu; ZHOU Zhiqiang; JIA Peiyun; LIN Jun

    2012-01-01

    YVO4:Eu nanocrystalline phosphors were successfully prepared at 400 ℃ in equal moles of NaNO3 and KNO3 molten salts.NaOH concentration and annealing temperature played important roles in phase purity and crystallinity of the nanocrystallines,and the optimum NaOH concentration and annealing temperature were 6∶40 and 400 ℃,respectively.The nanocrystallines were well crystallized with a cubic morphology in an average grain size of 18 nm.Upon excitation of the vanadate groups at 314 nm,YVO4:Eu nanocrystallines exhibited the characteristic emission of Eu3+,which indicated that there was an energy transfer from vanadate groups to Eu3+.Moreover,the influence of superficial effect,especially the dangling bonds on the structure and luminescent properties of the nanocrystallines was discussed in detail.

  9. Ablation studies using a diode-pumped Nd:YVO4 micro-laser

    Science.gov (United States)

    Pervolaraki, M.; Dyer, P. E.; Monk, P.

    We report an investigation of ablating several materials using a nanosecond pulse duration Nd:YVO4 micro-laser operating at wavelengths of 1064 and 532 nm and high pulse-repetition rate (ballistic pendulum measurements and scanning electron microscopy are used to characterise the interaction. It is shown that good-quality micro-scale features can be produced in polyimide, gold foils and silicon targets by ablation using this laser.

  10. The double-end-pumped cubic Nd:YVO4 laser: Temperature distribution and thermal stress

    Indian Academy of Sciences (India)

    P Elahi; S Morshedi

    2010-01-01

    Thermal effects of a double-end-pumped cubic Nd:YVO4 laser crystal are investigated in this paper. A detailed analysis of temperature distribution and thermal stress in cubic crystal with circular shape pumping is discussed. It has been shown that by considering the total input powers as constant, the double-end-pumped configurations with equal pump power can be considered as having a minimum thermal effect with respect to the other end-pumped configuration.

  11. Index and gain gratings in Nd-YVO4 - Applications to speckle vibrometry and photoacoustic detection

    Science.gov (United States)

    Jayet, Baptiste; Huignard, Jean-Pierre; Ramaz, François

    2017-06-01

    We perform wave mixing and dynamic holography by exploiting gain saturation in diode pumped laser media like Nd-YVO4. Such crystals offer the possibility of performing adaptive gain interferometers with a sub ms response time, typically between 100- 200μs. This temporal response is of great interest for applications such as speckle interferometry and acousto-optic detection for tissue imaging in biophotonics. In this work we operate in new conditions of high sensitivity with a linear response due to a refractive index contribution in the gain media. It originates from the wavelength mismatch of about 0.1 nm between the incident Nd-YAG probe laser and laser transition in diode pumped Nd-YVO4 amplifier. This permits the recording of two types of volume holograms respectively a gain and a phase volume holograms. It is the index grating which provides a linear response to incident low phase modulation at frequencies higher than 10 kHz. Experimental results confirm this behavior for adaptive interferometry and speckle vibrometry. In addition, the fast response makes the two wave mixing interaction in Nd-YVO4 very interesting for the optical detection of large bandwith photoacoustic waves excited by a pulsed ns Q-Switch laser at 532 nm. Temporal photoacoustic signals and images of small objects behind a scattering media will be shown.

  12. ANISOTROPY OF OPTICAL ABSORPTION INTENSITY IN Tm3+ DOPED YVO4 CRYSTALS

    Institute of Scientific and Technical Information of China (English)

    LIN XIU-HUA; JIANG BING-XI

    2000-01-01

    Seven absorption group-bands (1D2, 1G4, 3F2, 3F3, 3H4, 3H5, 3F4) of Tm3+ in YVO4 single crystals have been observed in the orientation absorption spectra recorded in the spectral range from 200 to 4000 nm at 300K.The integrated absorption cross section for each group-band was accurately evaluated. On the assumption that the anisotropy of this uni-axial crystal is small, the Judd-Ofelt theory was extended for the calculation of 4f-4f transition intensities of Tm3+ in YVO4. Two sets of phenomenological intensity parameters were derived from a least-squares-fit procedure. For c-axis cut sample we have Ω2=10.18 (10-20cm2), Ω4=1.96 (10-20cm2), Ω6=0.75 (10-20cm2). For a-axis cut sample we have Ω2 = 8.20 (10-20cm2), Ω4 = 2.47 (10-20cm2), Ω6 = 0.91 (10-20cm2). The anisotropy of the optical absorption intensities of Tm3+:YVO4 was theoretically analyzed in detail.

  13. Fabrication and characterization of YVO4:Eu3+ nanomaterials by the microwave technique

    Institute of Scientific and Technical Information of China (English)

    Tran Thu Huong; Vu Duc Tu; Tran Kim Anh; Le Thi Vinh; Le Quoc Minh

    2011-01-01

    Fabrication and characterization of YVO4:Eu3+ nanophosphors prepared by microwave (MW) irradiation assisted soft template synthesis were reported.The effects of synthesis conditions such as different powers of MW irradiation,pH values and concentration of reaction materials on properties of nanophosphor were also investigated to obtain the controllable size,morphology and high luminescence efficiency.Morphology,crystalline structure,and optical properties were characterized by field emission scanning electron microscopy (FE-SEM),X-ray diffraction (XRD) and fluorescence spectroscopy,respectively.The results showed that YVO4:Eu3+ nanophosphors were obtained by using diethyleneglycol (DEG) as soft template,with pH values in the range of 4 to 12,upon microwave irradiation from 300 to 900 W,at temperature of 80 ℃.The high fluorescent YVO4:Eu3+ nanocrystals obtained with size from 15 nm down to 8 nm are more effective to develop an ultrahigh sensitive fluorescent label for biomolecule,cell and tissue.

  14. Nd:YVO4 amplifier for ultrafast low-power lasers.

    Science.gov (United States)

    Agnesi, Antonio; Carrà, Luca; Piccoli, Riccardo; Pirzio, Federico; Reali, Giancarlo

    2012-09-01

    An Nd:YVO4 amplifier consisting of two modules end pumped at 808 nm at 30 W total absorbed power has been designed for efficient, diffraction-limited amplification of ultrafast pulses from low-power seeders. We investigated amplification with a 50 mW, 7 ps Nd:YVO4 oscillator, a 2 mW, 15 ps Yb fiber laser, and a 30 mW, 300 fs Nd:glass laser. Output power as high as 9.5 W with 8 ps pulses was achieved with the 250 MHz vanadate seeder, whereas the 20 MHz fiber laser was amplified to 6 W. The femtosecond seeder allowed extracting Fourier-limited 4 ps pulses at 7 W output power. To our knowledge, these are the shortest pulses from any Nd:YVO4 laser device with at least 7 W output power. This suggests a novel approach to exploit the gain bandwidth of vanadate amplifiers with high output power levels. Such amplifier technology promises to offer an interesting alternative to high-power thin disk oscillators at few picoseconds duration, as well as to regenerative amplifiers with low-repetition-rate fiber seeders.

  15. Punctuated Evolution of Volcanology: An Observatory Perspective

    Science.gov (United States)

    Burton, W. C.; Eichelberger, J. C.

    2010-12-01

    Volcanology from the perspective of crisis prediction and response-the primary function of volcano observatories-is influenced both by steady technological advances and singular events that lead to rapid changes in methodology and procedure. The former can be extrapolated somewhat, while the latter are surprises or shocks. Predictable advances include the conversion from analog to digital systems and the exponential growth of computing capacity and data storage. Surprises include eruptions such as 1980 Mount St Helens, 1985 Nevado del Ruiz, 1989-1990 Redoubt, 1991 Pinatubo, and 2010 Eyjafjallajokull; the opening of GPS to civilian applications, and the advent of an open Russia. Mount St Helens switched the rationale for volcanology in the USGS from geothermal energy to volcano hazards, Ruiz and Pinatubo emphasized the need for international cooperation for effective early warning, Redoubt launched the effort to monitor even remote volcanoes for purposes of aviation safety, and Eyjafjallajokull hammered home the need for improved ash-dispersion and engine-tolerance models; better GPS led to a revolution in volcano geodesy, and the new Russian Federation sparked an Alaska-Kamchatka scientific exchange. The pattern has been that major funding increases for volcano hazards occur after these unpredictable events, which suddenly expose a gap in capabilities, rather than out of a calculated need to exploit technological advances or meet a future goal of risk mitigation. It is up to the observatory and national volcano hazard program to leverage these sudden funding increases into a long-term, sustainable business model that incorporates both the steadily increasing costs of staff and new technology and prepares for the next volcano crisis. Elements of the future will also include the immediate availability on the internet of all publically-funded volcano data, and subscribable, sophisticated hazard alert systems that run computational, fluid dynamic eruption models. These

  16. Global Volcano Model

    Science.gov (United States)

    Sparks, R. S. J.; Loughlin, S. C.; Cottrell, E.; Valentine, G.; Newhall, C.; Jolly, G.; Papale, P.; Takarada, S.; Crosweller, S.; Nayembil, M.; Arora, B.; Lowndes, J.; Connor, C.; Eichelberger, J.; Nadim, F.; Smolka, A.; Michel, G.; Muir-Wood, R.; Horwell, C.

    2012-04-01

    Over 600 million people live close enough to active volcanoes to be affected when they erupt. Volcanic eruptions cause loss of life, significant economic losses and severe disruption to people's lives, as highlighted by the recent eruption of Mount Merapi in Indonesia. The eruption of Eyjafjallajökull, Iceland in 2010 illustrated the potential of even small eruptions to have major impact on the modern world through disruption of complex critical infrastructure and business. The effects in the developing world on economic growth and development can be severe. There is evidence that large eruptions can cause a change in the earth's climate for several years afterwards. Aside from meteor impact and possibly an extreme solar event, very large magnitude explosive volcanic eruptions may be the only natural hazard that could cause a global catastrophe. GVM is a growing international collaboration that aims to create a sustainable, accessible information platform on volcanic hazard and risk. We are designing and developing an integrated database system of volcanic hazards, vulnerability and exposure with internationally agreed metadata standards. GVM will establish methodologies for analysis of the data (eg vulnerability indices) to inform risk assessment, develop complementary hazards models and create relevant hazards and risk assessment tools. GVM will develop the capability to anticipate future volcanism and its consequences. NERC is funding the start-up of this initiative for three years from November 2011. GVM builds directly on the VOGRIPA project started as part of the GRIP (Global Risk Identification Programme) in 2004 under the auspices of the World Bank and UN. Major international initiatives and partners such as the Smithsonian Institution - Global Volcanism Program, State University of New York at Buffalo - VHub, Earth Observatory of Singapore - WOVOdat and many others underpin GVM.

  17. Applications of geophysical methods to volcano monitoring

    Science.gov (United States)

    Wynn, Jeff; Dzurisin, Daniel; Finn, Carol A.; Kauahikaua, James P.; Lahusen, Richard G.

    2006-01-01

    The array of geophysical technologies used in volcano hazards studies - some developed originally only for volcano monitoring - ranges from satellite remote sensing including InSAR to leveling and EDM surveys, campaign and telemetered GPS networks, electronic tiltmeters and strainmeters, airborne magnetic and electromagnetic surveys, short-period and broadband seismic monitoring, even microphones tuned for infrasound. They include virtually every method used in resource exploration except large-scale seismic reflection. By “geophysical ” we include both active and passive methods as well as geodetic technologies. Volcano monitoring incorporates telemetry to handle high-bandwith cameras and broadband seismometers. Critical geophysical targets include the flux of magma in shallow reservoir and lava-tube systems, changes in active hydrothermal systems, volcanic edifice stability, and lahars. Since the eruption of Mount St. Helens in Washington State in 1980, and the eruption at Pu’u O’o in Hawai’i beginning in 1983 and still continuing, dramatic advances have occurred in monitoring technology such as “crisis GIS” and lahar modeling, InSAR interferograms, as well as gas emission geochemistry sampling, and hazards mapping and eruption predictions. The on-going eruption of Mount St. Helens has led to new monitoring technologies, including advances in broadband Wi-Fi and satellite telemetry as well as new instrumentation. Assessment of the gap between adequate monitoring and threat at the 169 potentially dangerous Holocene volcanoes shows where populations are dangerously exposed to volcanic catastrophes in the United States and its territories . This paper focuses primarily on Hawai’ian volcanoes and the northern Pacific and Cascades volcanoes. The US Geological Survey, the US National Park System, and the University of Utah cooperate in a program to monitor the huge Yellowstone volcanic system, and a separate observatory monitors the restive Long Valley

  18. A facile synthesis of luminescent YVO4:Eu3+ hollow microspheres in virtue of template function of the SDS-PEG soft clusters

    Science.gov (United States)

    Wang, Juan; Yan, Yinglin; Hojamberdiev, Mirabbos; Ruan, Xiaoguang; Cai, Anjiang; Xu, Yunhua

    2012-08-01

    Hollow europium-doped yttrium orthovanadate (YVO4:Eu3+) microspheres were fabricated via a sodium dodecyl sulfate (SDS)-polyethylene glycol (PEG)-assisted hydrothermal technique. The as-synthesized hollow YVO4:Eu3+ microspheres were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). The obtained results showed that the morphology and size of the hollow microspheres have a strong dependence on the hydrothermal reaction time of the YVO4:Eu3+ powders. It is believed that the SDS-PEG clusters perform a function of dual soft-template that results in a unique template-induced secondary assembly in the one-pot synthesis of hollow YVO4:Eu3+ microspheres. The photoluminescence measurement revealed that the YVO4:Eu3+ powders with a spherical hollow shape have better red luminescence compared to the YVO4:Eu3+ solid microspheres. As a result, the controlled synthesis of hollow YVO4:Eu3+ microspheres not only has a great theoretical significance in studying the three-dimensional control and selective synthesis of inorganic materials but also benefits the potential applications based on hollow YVO4:Eu3+ microspheres owing to reducing the usage of expensive rare-earth elements.

  19. Petrologic insights into basaltic volcanism at historically active Hawaiian volcanoes: Chapter 6 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Helz, Rosalind L.; Clague, David A.; Sisson, Thomas W.; Thornber, Carl R.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Study of the petrology of Hawaiian volcanoes, in particular the historically active volcanoes on the Island of Hawai‘i, has long been of worldwide scientific interest. When Dr. Thomas A. Jaggar, Jr., established the Hawaiian Volcano Observatory (HVO) in 1912, detailed observations on basaltic activity at Kīlauea and Mauna Loa volcanoes increased dramatically. The period from 1912 to 1958 saw a gradual increase in the collection and analysis of samples from the historical eruptions of Kīlauea and Mauna Loa and development of the concepts needed to evaluate them. In a classic 1955 paper, Howard Powers introduced the concepts of magnesia variation diagrams, to display basaltic compositions, and olivine-control lines, to distinguish between possibly comagmatic and clearly distinct basaltic lineages. In particular, he and others recognized that Kīlauea and Mauna Loa basalts must have different sources.

  20. Foci of Volcanoes

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, I.

    1974-01-01

    One may assume a center of volcanic activities beneath the edifice of an active volcano, which is here called the focus of the volcano. Sometimes it may be a ''magma reservoir''. Its depth may differ with types of magma and change with time. In this paper, foci of volcanoes are discussed from the viewpoints of four items: (1) Geomagnetic changes related with volcanic activities; (2) Crustal deformations related with volcanic activities; (3) Magma transfer through volcanoes; and (4) Subsurface structure of calderas.

  1. Optical processes in YVO{sub 4}:Eu{sup 3+}across zircon-to-scheelite phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Mahlik, Sebastian, E-mail: s.mahlik@ug.edu.pl [Institute of Experimental Physics, University of Gdansk, WitaStwosza 57, 80-952 Gdańsk (Poland); Lazarowska, Agata; Szczodrowski, Karol [Institute of Experimental Physics, University of Gdansk, WitaStwosza 57, 80-952 Gdańsk (Poland); Grinberg, Marek, E-mail: fizmgr@ug.edu.pl [Institute of Experimental Physics, University of Gdansk, WitaStwosza 57, 80-952 Gdańsk (Poland); Cavalli, Enrico [Department of Chemistry, Università di Parma, Parma (Italy); Boutinaud, Philippe [Clermont Université, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France)

    2015-09-15

    The luminescence processes across zircon-to-scheelite phase transition in undoped YVO{sub 4} and Eu{sup 3+}-doped YVO{sub 4} are investigated by measuring the Raman, excitation and emission spectra and decay characteristics of the compounds with respect to high hydrostatic pressure up to 200 kbar. The scheelite polymorphs obtained after releasing the high pressure show no luminescence when undoped, even down to 10 K, but when activated with Eu{sup 3+} exhibit the characteristic scheelite-related Eu{sup 3+} emission but with low intensity. This emission is produced upon UV excitation in zircon inclusions that remain after the pressure treatment. - Highlights: • We present the pressure dependence of luminescence properties of YVO{sub 4}:Eu{sup 3+}. • The application of a hydrostatic pressure of ≈7.5 GPa leads to a phase transition from zircon to scheelite phase YVO{sub 4}. • Eu{sup 3+} luminescence in scheelite YVO{sub 4}:Eu{sup 3+} cannot be produced upon excitation in the fundamental states.

  2. European Southern Observatory

    CERN Multimedia

    1970-01-01

    Professor A. Blaauw, Director general of the European Southern Observatory, with George Hampton on his right, signs the Agreement covering collaboration with CERN in the construction of the large telescope to be installed at the ESO Observatory in Chile.

  3. Solar Dynamics Observatory

    Data.gov (United States)

    National Aeronautics and Space Administration — A searchable database of all Solar Dynamics Observatory data including EUV, magnetograms, visible light and X-ray. SDO: The Solar Dynamics Observatory is the first...

  4. Efficient yellow beam generation by intracavity sum frequency mixing in DPSS Nd:YVO4 laser

    Indian Academy of Sciences (India)

    A J Singh; P K Gupta; S K Sharma; P K Mukhopadhyay; K S Bindra; S M Oak

    2014-02-01

    We present our studies on dual wavelength operation using a single Nd:YVO4 crystal and its intracavity sum frequency generation by considering the influence of the thermal lensing effect on the performance of the laser. A KTP crystal cut for type-II phase matching was used for intracavity sum frequency generation in the cavity at an appropriate location for efficient and stable yellow output power. More than 550 mW of stable CW yellow-orange beam at 593.5 nm with beam quality parameter (2) ∼ 4.3 was obtained. The total pump to yellow beam conversion efficiency was estimated to be 3.83%.

  5. Optical Fiber Pumped High Repetition Rate and High Power Nd:YVO4 Picosecond Regenerative Amplifier

    Directory of Open Access Journals (Sweden)

    Zhen-Ao Bai

    2015-08-01

    Full Text Available We report a stable optical fiber pumped Nd:YVO4 all solid state regenerative amplifier with all fiber picosecond laser as seed source. 888 nm Yb optical fiber lasers was chosen as pump source to reduce quantum defect for improved thermal performance. At the repetition rate of 99.6 kHz, maximum power of 19.63 W with 36 ps pulse duration were achieved when seeded by a 150 mW picosecond oscillator. The wavelength delivered was 1064.07 nm with spectral width of 0.14 nm.

  6. High Efficient LD-pumped Nd∶YVO4/ LBO Red Laser

    Institute of Scientific and Technical Information of China (English)

    ZHENG Quan; ZHAO Ling; TAN Huiming

    2001-01-01

    A design of high efficient LD-pumped Nd∶YVO4/LBO red laser was reported in this paper. For the first time, type-I critical phase-matched LBO was used for 1.342 μm intracavity frequency-doubling to obtain 671 nm red laser. With 760 mW incident pump power, 78 mW TEM00 mode red laser output was obtained, the optical-to-optical conversion up to 10%. Measurements showed the beam divergent angle less than 0.5 mrad, polarization degree more than 100∶1 and power instability in 48 hours less than ±2%.

  7. Linearly polarized pumped passively Q-switched Nd:YVO4 microchip laser for Ince-Gaussian laser modes with controllable orientations

    Science.gov (United States)

    He, Hong-Sen; Zhang, Ming-Ming; Dong, Jun; Ueda, Ken-Ichi

    2016-12-01

    A tilted, linearly polarized laser diode end-pumped Cr4+:YAG passively Q-switched a-cut Nd:YVO4 microchip laser for generating numerous Ince-Gaussian (IG) laser modes with controllable orientations has been demonstrated by selecting the crystalline orientation of an a-cut Nd:YVO4 crystal. The same IG laser mode with different orientations has been achieved with the same absorbed pump power in a passively Q-switched Nd:YVO4 microchip laser under linearly polarized pumping when the incident pump power and the crystalline orientation of an a-cut Nd:YVO4 crystal are both properly selected. The significant improvement of pulsed laser performance of controllable IG modes has been achieved by selecting the crystalline orientation of an a-cut Nd:YVO4 crystal. The maximum pulse energy is obtained along the a-axis of an a-cut Nd:YVO4 crystal and the highest peak power is achieved along the c-axis of an a-cut Nd:YVO4 crystal, respectively, which has potential applications on quantum computation and optical manipulation. The generation of controllable IG laser modes in microchip lasers under linearly polarized pumping provides a convenient and universal way to control IG laser mode numbers with anisotropic crystal as a gain medium.

  8. The High-Altitude Water Cherenkov Observatory

    Science.gov (United States)

    Mostafá, Miguel A.

    2014-10-01

    The High-Altitude Water Cherenkov (HAWC) observatory is a large field of view, continuously operated, TeV γ-ray experiment under construction at 4,100 m a.s.l. in Mexico. The HAWC observatory will have an order of magnitude better sensitivity, angular resolution, and background rejection than its predecessor, the Milagro experiment. The improved performance will allow us to detect both the transient and steady emissions, to study the Galactic diffuse emission at TeV energies, and to measure or constrain the TeV spectra of GeV γ-ray sources. In addition, HAWC will be the only ground-based instrument capable of detecting prompt emission from γ-ray bursts above 50 GeV. The HAWC observatory will consist of an array of 300 water Cherenkov detectors (WCDs), each with four photomultiplier tubes. This array is currently under construction on the flanks of the Sierra Negra volcano near the city of Puebla, Mexico. The first 30 WCDs (forming an array approximately the size of Milagro) were deployed in Summer 2012, and 100 WCDs will be taking data by May, 2013. We present in this paper the motivation for constructing the HAWC observatory, the status of the deployment, and the first results from the constantly growing array.

  9. The high-altitude water Cherenkov Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Mostafa, Miguel A., E-mail: miguel@psu.edu [Department of Physics, Colorado State University, Ft Collins, CO (United States)

    2014-07-01

    The High-Altitude Water Cherenkov (HAWC) observatory is a large field of view, continuously operated, TeV γ -ray experiment under construction at 4,100ma.s.l. in Mexico. The HAWC observatory will have an order of magnitude better sensitivity, angular resolution, and background rejection than its predecessor, the Milagro experiment. The improved performance will allow to detect both the transient and steady emissions, to study the Galactic diffuse emission at TeV energies, and to measure or constrain the TeV spectra of GeV γ -ray sources. In addition, HAWC will be the only ground-based instrument capable of detecting prompt emission from γ -ray bursts above 50 GeV. The HAWC observatory will consist of an array of 300 water Cherenkov detectors (WCDs), each with four photomultiplier tubes. This array is currently under construction on the flanks of the Sierra Negra volcano near the city of Puebla, Mexico. The first 30 WCDs (forming an array approximately the size of Milagro) were deployed in Summer 2012, and 100 WCDs will be taking data by May, 2013. We present in this paper the motivation for constructing the HAWC observatory, the status of the deployment, and the first results from the constantly growing array. (author)

  10. Volcano Monitoring Using Google Earth

    Science.gov (United States)

    Cameron, W.; Dehn, J.; Bailey, J. E.; Webley, P.

    2009-12-01

    At the Alaska Volcano Observatory (AVO), remote sensing is an important component of its daily monitoring of volcanoes. AVO’s remote sensing group (AVORS) primarily utilizes three satellite datasets; Advanced Very High Resolution Radiometer (AVHRR) data, from the National Oceanic and Atmospheric Administration’s (NOAA) Polar Orbiting Satellites (POES), Moderate Resolution Imaging Spectroradiometer (MODIS) data from the National Aeronautics and Space Administration’s (NASA) Terra and Aqua satellites, and NOAA’s Geostationary Operational Environmental Satellites (GOES) data. AVHRR and MODIS data are collected by receiving stations operated by the Geographic Information Network of Alaska (GINA) at the University of Alaska’s Geophysical Institute. An additional AVHRR data feed is supplied by NOAA’s Gilmore Creek satellite tracking station. GOES data are provided by the Naval Research Laboratory (NRL), Monterey Bay. The ability to visualize these images and their derived products is critical for the timely analysis of the data. To this end, AVORS has developed javascript web interfaces that allow the user to view images and metadata. These work well for internal analysts to quickly access a given dataset, but they do not provide an integrated view of all the data. To do this AVORS has integrated its datasets with Keyhole Markup Language (KML) allowing them to be viewed by a number of virtual globes or other geobrowsers that support this code. Examples of AVORS’ use of KML include the ability to browse thermal satellite image overlays to look for signs of volcanic activity. Webcams can also be viewed interactively through KML to confirm current activity. Other applications include monitoring the location and status of instrumentation; near real-time plotting of earthquake hypocenters; mapping of new volcanic deposits using polygons; and animated models of ash plumes, created by a combination of ash dispersion modeling and 3D visualization packages.

  11. THE GEOLOGIC RISK IN THE LAKE KIVU BASIN AREA PRODUCTED BY EARTHQUAKES. Case of the February 3th 2008 earthquake. By: L.M.Bagalwa(1), F.Lukaya(1), M.Burume(2), J.Moeyerson(3) (1): Goma Volcano Observatory, D.R.Congo (2): Naturals Sciences Research Center

    Science.gov (United States)

    Bagalwa Rukeza, Montfort

    2010-05-01

    The eastern Democratic Republic of Congo is prone to earthquakes of magnitude greater than or equal to 4 on the Richter scale. The western edge of Lake Kivu, the most populated part of the region is no exception to the solicitation of these earthquakes. Since 1997, the western basin of Lake Kivu is experiencing intense seismicity, several earthquakes of great intensity, magnitude greater than or equal to 4 develop major destructive phenomena. These include the 1997 earthquake (M = 4.7) 2000 (M = 4.6 and 5.4), 2002 (M = 4.9, 5.2, 6.1 and 24 October 2002 M = 6.2) of February 3rd 2008 (M = 6). Earthquakes of Kalehe on October 24th 2002 and Birava, February 3rd 2008 have resulted deformations of soil, human and material damage. This latest natural disaster ever known in the south-western basin of Lake Kivu has attracted our scientific curiosity we go there to inquire into its causes and consequences in this region. The basin of Lake Kivu is affected by transform faults emerging (MUKONKI & CHOROWICZ, 1980, quoted by K.S.KAVOTHA & ali, 1990) that delimit the Rift were intersecting at the level of Lake Kivu. We Consider the seismicity, volcanism and uplift of the basin of Lake Kivu as a sign of fracturing under way to delimit a plate tectonics formed (Wong and Von Herzen, 1974, quoted by KSKAVOTHA et al, 1990). The physiography of Lake Kivu is dominated by the fault which borders the western shore and one which intersects the island of Idjwi. The telemetry data of Goma Volcano Observatory added to those of the seismographic station of Lwiro have always revealed a pattern of epicenters clearer in Lake Kivu. In correlation with the faults of the region, earthquakes affect mainly the western edge of Lake Kivu and the island of Idjwi with increasing density from north to south (K.S.KAVOTHA et al, 1990). The great earthquake of Lake Kivu basin on February 03rd 2008, of magnitude 6 on the Richter scale occurred at 07 hours 34 minutes 12 seconds GMT, about 20 km north of Bukavu

  12. Influence of the laser-diode temperature on crystal absorption and output power in an end-pumped Nd:YVO4 laser

    Indian Academy of Sciences (India)

    Ebrahim Safari

    2011-01-01

    In this work, we studied the influence of heat loaded into the laser crystal in an endpumped solid-state Nd:YVO4 high power laser. We have shown experimentally that the optimum value of the laser-diode temperature for the maximum pump power absorption by the Nd:YVO4 crystal and the maximum Nd:YVO4 laser output power are approximately similar to that of a system of the low power type, but by increasing the pump power, different values can be obtained.

  13. Catalog of earthquake hypocenters at Alaskan volcanoes: January 1 through December 31, 2011

    Science.gov (United States)

    Dixon, James P.; Stihler, Scott D.; Power, John A.; Searcy, Cheryl K.

    2012-01-01

    Between January 1 and December 31, 2011, the Alaska Volcano Observatory (AVO) located 4,364 earthquakes, of which 3,651 occurred within 20 kilometers of the 33 volcanoes with seismograph subnetworks. There was no significant seismic activity above background levels in 2011 at these instrumented volcanic centers. This catalog includes locations, magnitudes, and statistics of the earthquakes located in 2011 with the station parameters, velocity models, and other files used to locate these earthquakes.

  14. Volcanoes - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This map layer includes Holocene volcanoes, which are those thought to be active in the last 10,000 years, that are within an extended area of the northern...

  15. Italian active volcanoes

    Institute of Scientific and Technical Information of China (English)

    RobertoSantacroce; RenawCristofolini; LuigiLaVolpe; GiovanniOrsi; MauroRosi

    2003-01-01

    The eruptive histories, styles of activity and general modes of operation of the main active Italian volcanoes,Etna, Vulcano, Stromboli, Vesuvio, Campi Flegrei and Ischia, are described in a short summary.

  16. Power scaling from buried depressed-cladding waveguides realized in Nd:YVO4 by femtosecond-laser beam writing

    Science.gov (United States)

    Salamu, Gabriela; Pavel, Nicolaie

    2016-10-01

    We report on output power performances obtained by diode-laser pumping of buried cladding-waveguides that were inscribed with a femtosecond-laser beam writing technique in several Nd:YVO4 media. Continuous-wave output power of 3.4 W at 1.06 μm for an absorbed pump power at 808 nm of 10.3 W was obtained from a circular waveguide of 100-μm diameter that was realized in a 6.9-mm long, 0.5-at% Nd:YVO4 crystal; the slope efficiency with respect to the absorbed pump power was 0.36. The pump at 880 nm, directly into the 4F3/2 emitting level, was used to improve the waveguide output characteristics. With an absorbed pump power of 9.8 W at 880 nm, the same waveguide yielded 4.4 W at 1.06 μm, whereas for emission at 1.34 μm the output power reached 1.7 W; the slope efficiency improved to 0.47 for laser emission at 1.06 μm and reached 0.24 for operation at 1.34 μm. Results recorded from similar waveguides that were inscribed in 0.7-at% Nd:YVO4 and 1.0-at% Nd:YVO4 crystals are presented.

  17. Redoubt Volcano: 2009 Eruption Overview

    Science.gov (United States)

    Bull, K. F.

    2009-12-01

    Redoubt Volcano is a 3110-m glaciated stratovolcano located 170 km SW of Anchorage, Alaska, on the W side of Cook Inlet. The edifice comprises a oil production in Cook Inlet was halted for nearly five months. Unrest began in August, 2008 with reports of H2S odor. In late September, the Alaska Volcano Observatory (AVO)’s seismic network recorded periods of volcanic tremor. Throughout the fall, AVO noted increased fumarolic emissions and accompanying ice- and snow-melt on and around the 1990 dome, and gas measurements showed elevated H2S and CO2 emissions. On January 23, seismometers recorded 48 hrs of intermittent tremor and discrete, low-frequency to hybrid events. Over the next 6 weeks, seismicity waxed and waned, an estimated 5-6 million m3 of ice were lost due to melting, volcanic gas emissions increased, and debris flows emerged repeatedly from recently formed ice holes near the 1990 dome, located on the crater’s N (“Drift”) side. On March 15, a phreatic explosion deposited non-juvenile ash from a new vent in the summit ice cap just S of the 1990 dome. Ash from the explosion rose to ~4500 m above sea level (asl). The plume was accompanied by weak seismicity. The first magmatic explosion occurred on March 22. Over the next two weeks, more than 19 explosions destroyed at least two lava domes and produced ash plumes that reached 6-18 km asl. Tephra was deposited along variable azimuths including trace to minor amounts on Anchorage and Kenai Peninsula communities, and reached Fairbanks, ~800 km to the N. Several lahars were produced by explosive disruption and melting of the “Drift” glacier. The largest lahars followed explosions on March 23 and April 4 and inundated the Drift River valley to the coast, causing temporary evacuation of the Drift River Oil Terminal, ~40 km from the vent. Time-lapse images captured pyroclastic flows and lahars in the “Drift” glacier valley during several of the explosions. Ballistics and pyroclastic flow deposits were

  18. Transient and near-edge absorption in YVO{sub 4} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Millers, D.; Pankratov, V.; Grigorjeva, L. [Institute of Solid State Physics, University of Latvia, Riga (Latvia); Yochum, H.M. [Department of Physics and Engineering, Sweet Briar College, VA (United States); Potera, P. [Mat-Phys Department, Institute of Physics, University of Rzeszow (Poland)

    2007-03-15

    The process of near-edge absorption annealing in air was studied up to 1500C in YVO{sub 4}. In this annealing process, two stages with activation energies of 0.16 eV and 0.38 eV were obtained. (Should combine to make this one paragraph)In addition to the annealing study, the transient absorption induced by pulsed electron beam excitation (270 keV, 8 ns) was completed on a set of YVO{sub 4} samples with different near-edge absorption levels in the spectral region 3.2-3.5 eV. The spectral range from {proportional_to}1.25 eV up to 3.0 eV is covered by strong transient absorption. Transient absorption spectra show at least three broad overlapping bands ({proportional_to}1.3 eV, {proportional_to}2.0 eV and {proportional_to}3.0 eV). The 3 eV peak position is close to the near-edge absorption band and correlation between transient absorption bands and absorption due to stable colour centers was studied. It is suggested that absorption bands at {proportional_to}1.3 eV and {proportional_to}2.0 eV are due to electron and hole polarons, correspondingly. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. DESIGN OF A 532nm Nd:YVO4/KTP SINGLE-FREQUENCY LASER

    Institute of Scientific and Technical Information of China (English)

    XU CHUN-LIN; SHEN NAI-CHENG; ZANG ER-JUN; SUN YI-MIN; LU HAI-NING; ZHAO KUN; ZHANG XUE-BIN

    2001-01-01

    A model of the laser-diode pumped solid-state laser is developed to deduce the minimum average radii of the pump beam in the solid medium, since the smaller the cavity waist, the higher the laser output power is expected to be.With an appropriate coupling system consisting of the collimating lens, prism pair and focusing lens, a diode-pumped single-frequency Nd:YVO4/KTP intracavity frequency-doubling cw laser has been demonstrated through the precise temperature control of the Nd:YVO4 crystal, the KTP crystal and the diode laser. The 532nm single-frequency output power of 40.4mW(in fact 55mW if the reflection loss of the triangular prism is taken into account)is obtained for an incident power of 515mW. It is derived theoretically and is verified in experiment that the frequency drift of the free-running laser can be reduced by increasing the cavity length.

  20. YvoA and CcpA Repress the Expression of chiB in Bacillus thuringiensis

    Science.gov (United States)

    Jiang, Kun; Li, Li-na; Pan, Jin-hua; Wang, Ting-ting; Chen, Yue-hua

    2015-01-01

    Bacillus thuringiensis produces chitinases, which are involved in its antifungal activity and facilitate its insecticidal activity. In our recent work, we found that a 16-bp sequence, drechiB (AGACTTCGTGATGTCT), downstream of the minimal promoter region of the chitinase B gene (chiB) was a critical site for the inducible expression of chiB in B. thuringiensis Bti75. In this work, we show that a GntR family transcriptional regulator (named YvoABt), which is homologous to YvoA of Bacillus subtilis, can specifically bind to the drechiB oligonucleotide sequences in vitro by using electrophoretic mobility shift assays (EMSAs) and isothermal titration calorimetry (ITC) assays. The results of quantitative real-time reverse transcription-PCR (qRT-PCR) and Western blotting indicated that deletion of yvoA caused an ∼7.5-fold increase in the expression level of chiB. Furthermore, binding of purified YvoABt to its target DNA could be abolished by glucosamine-6-phosphate (GlcN-6-P). We also confirmed, in the presence of the phosphoprotein Hpr-Ser45-P, that purified CcpABt bound specifically to the promoter of chiB, which contains the “crechiB” sequence (ATAAAGCGTTTACA). According to the results of qRT-PCR and Western blotting, deletion of ccpA resulted in a 39-fold increase in the chiB expression level, and glucose no longer influenced the expression of chiB. We confirm that chiB is negatively controlled by both CcpABt and YvoABt in Bti75. PMID:26162881

  1. The effect of urea:nitrate ratio on the structure and luminescence properties of YVO4:Dy3+ phosphors

    Science.gov (United States)

    Foka, K. E.; Dejene, B. F.; Swart, H. C.

    2016-01-01

    YVO4:Dy3+ phosphor has been successfully synthesised using combustion method. The dependence of the properties of YVO4:Dy3+ phosphor upon urea:nitrate concentration was investigated. The single tetragonal phase was observed by x-ray diffraction spectra. A highly crystalline YVO4:Dy3+ sample was obtained when increasing the ratio of the urea to 2. The estimated crystalline sizes from the Scherrer's formula were found to be 20, 38, 33, 30, and 27 nm for the sample prepared with the ratio of 1, 2, 2.5, 3 and 4, respectively. The formation of agglomerated particles was observed by Scanning electron microscope images and it was observed that when increasing the concentration of urea further, flake-like particles formed. The diffuse reflectance spectra of YVO4:Dy3+ with various ratios of urea indicated that the determined optical band gap was ranging from 3.3 to 2.3 eV. Luminescence properties of YVO4:Dy3+ showed that the phosphor emit yellow colour at 573 nm and blue colour at 482 nm corresponding to 4F9/2→6H13/2 and 4F9/2→6H15/2 transitions, respectively. A very weak band at 663 nm which correspond to the 4F9/2→6H11/2 transition was also observed. It was found that the Photoluminescent emission intensity increased with an increase in the ratio of urea and reached a maximum at 2 then decreased when increasing the ratio of urea further.

  2. YvoA and CcpA Repress the Expression of chiB in Bacillus thuringiensis.

    Science.gov (United States)

    Jiang, Kun; Li, Li-na; Pan, Jin-hua; Wang, Ting-ting; Chen, Yue-hua; Cai, Jun

    2015-10-01

    Bacillus thuringiensis produces chitinases, which are involved in its antifungal activity and facilitate its insecticidal activity. In our recent work, we found that a 16-bp sequence, drechiB (AGACTTCGTGATGTCT), downstream of the minimal promoter region of the chitinase B gene (chiB) was a critical site for the inducible expression of chiB in B. thuringiensis Bti75. In this work, we show that a GntR family transcriptional regulator (named YvoABt), which is homologous to YvoA of Bacillus subtilis, can specifically bind to the drechiB oligonucleotide sequences in vitro by using electrophoretic mobility shift assays (EMSAs) and isothermal titration calorimetry (ITC) assays. The results of quantitative real-time reverse transcription-PCR (qRT-PCR) and Western blotting indicated that deletion of yvoA caused an ∼7.5-fold increase in the expression level of chiB. Furthermore, binding of purified YvoABt to its target DNA could be abolished by glucosamine-6-phosphate (GlcN-6-P). We also confirmed, in the presence of the phosphoprotein Hpr-Ser₄₅-P, that purified CcpABt bound specifically to the promoter of chiB, which contains the "crechiB" sequence (ATAAAGCGTTTACA). According to the results of qRT-PCR and Western blotting, deletion of ccpA resulted in a 39-fold increase in the chiB expression level, and glucose no longer influenced the expression of chiB. We confirm that chiB is negatively controlled by both CcpABt and YvoABt in Bti75.

  3. VALVE: Volcano Analysis and Visualization Environment

    Science.gov (United States)

    Cervelli, D. P.; Cervelli, P.; Miklius, A.; Krug, R.; Lisowski, M.

    2002-12-01

    Modern volcano observatories collect data using a wide variety of instruments. Visualizing these disparate data on a common time base is critical to interpreting and reacting to geophysical changes. With this in mind, the Hawaiian Volcano Observatory (HVO) created Valve, the Volcano Analysis and Visualization Environment. Valve integrates a wide range of both continuous and discontinuous data sources into a common, internet web-browser based interface that allows scientists to interactively select and visualize these data on a common time base and, if appropriate, in three dimensions. Advances in modern internet browser technology allow for a truly interactive user-interface experience that could previously only be found in stand-alone applications--all while maintaining client platform independence and network portability. This system aids more traditional in-depth analysis by providing a common front-end to retrieving raw data. In most cases, the raw data are being served from an SQL database, a system that lends itself to quickly retrieving, logically arranging, and safely storing data. Beyond Valve's visualization capabilities, the system also provides a variety of tools for time series analysis and source modeling. For example, a user could load several tilt and GPS time series, estimate co-seismic or co-intrusive deformation, and then model the event with an elastic point source or dislocation. From the source model, Coulomb stress changes could be calculated and compared to pre- and post-event hypocenter distribution. Employing a heavily object-oriented design, Valve is easily extensible, modular, portable, and remarkably cost efficient. Quickly visualizing arbitrary data is a trivial matter, while implementing methods for permanent, continuous data streams requires only minimal programming. Portability is ensured by using software that is readily available on a wide variety of operating systems; cost efficiency is achieved by using software that is open

  4. Mauna Loa--history, hazards and risk of living with the world's largest volcano

    Science.gov (United States)

    Trusdell, Frank A.

    2012-01-01

    Mauna Loa on the Island Hawaiʻi is the world’s largest volcano. People residing on its flanks face many hazards that come with living on or near an active volcano, including lava flows, explosive eruptions, volcanic smog, damaging earthquakes, and local tsunami (giant seawaves). The County of Hawaiʻi (Island of Hawaiʻi) is the fastest growing County in the State of Hawaii. Its expanding population and increasing development mean that risk from volcano hazards will continue to grow. U.S. Geological Survey (USGS) scientists at the Hawaiian Volcano Observatory (HVO) closely monitor and study Mauna Loa Volcano to enable timely warning of hazardous activity and help protect lives and property.

  5. Cook Inlet and Kenai Peninsula, Alaska ESI: VOLCANOS (Volcano Points)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains the locations of volcanos in Cook Inlet and Kenai Peninsula, Alaska. Vector points in the data set represent the location of the volcanos....

  6. Efficient second harmonic generation of double-end diffusion-bonded Nd:YVO4 self-Raman laser producing 7.9 W yellow light

    National Research Council Canada - National Science Library

    Zhu, Haiyong; Duan, Yanmin; Zhang, Ge; Huang, Chenghui; Wei, Yong; Shen, Hongyuan; Zheng, Yiqun; Huang, Lingxiong; Chen, Zhenqiang

    2009-01-01

    .... A 30-mm-length double-end diffusion-bonded Nd:YVO(4) crystal was utilized for efficient self-Raman laser operation by reducing the thermal effects and increasing the interaction length for the stimulated Raman scattering...

  7. Efficient second harmonic generation of double-end diffusion-bonded Nd:YVO_4 self-Raman laser producing 7.9 W yellow light

    National Research Council Canada - National Science Library

    Haiyong Zhu; Yanmin Duan; Ge Zhang; Chenghui Huang; Yong Wei; Hongyuan Shen; Yiqun Zheng; Lingxiong Huang; Zhenqiang Chen

    2009-01-01

    .... A 30-mm-length double-end diffusion-bonded Nd:YVO_4 crystal was utilized for efficient self-Raman laser operation by reducing the thermal effects and increasing the interaction length for the stimulated Raman scattering...

  8. A Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser for controllable high-order Hermite-Gaussian modes

    Science.gov (United States)

    Dong, Jun; He, Yu; Bai, Sheng-Chuang; Ueda, Ken-ichi; Kaminskii, Alexander A.

    2016-09-01

    A nanosecond, high peak power, passively Q-switched laser for controllable Hermite-Gaussian (HG) modes has been achieved by manipulating the saturated inversion population inside the gain medium. The stable HG modes are generated in a Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser by applying a tilted pump beam. The asymmetrical saturated inversion population distribution inside the Nd:YVO4 crystal for desirable HG modes is manipulated by choosing the proper pump beam diameter and varying pump power. A HG9,8 mode passively Q-switched Nd:YVO4 microchip laser with average output power of 265 mW has been obtained. Laser pulses with a pulse width of 7.3 ns and peak power of over 1.7 kW working at 21 kHz have been generated in the passively Q-switched Nd:YVO4 microchip laser.

  9. Beijing Ancient Observatory

    Science.gov (United States)

    Shi, Yunli

    The Beijing Ancient Observatory is now the only complete example of an observatory from the seventeenth century in the world. It is a monument to the prosperity of astronomy in traditional China. Its instruments are emblems of the encounter and amalgamation of Chinese and European Science in the seventeenth and eighteenth centuries.

  10. Zelenchukskaya Radio Astronomical Observatory

    Science.gov (United States)

    Smolentsev, Sergey; Dyakov, Andrei

    2013-01-01

    This report summarizes information about Zelenchukskaya Radio Astronomical Observatory activities in 2012. Last year a number of changes took place in the observatory to improve some technical characteristics and to upgrade some units to the required status. The report provides an overview of current geodetic VLBI activities and gives an outlook for the future.

  11. Svetloe Radio Astronomical Observatory

    Science.gov (United States)

    Smolentsev, Sergey; Rahimov, Ismail

    2013-01-01

    This report summarizes information about the Svetloe Radio Astronomical Observatory activities in 2012. Last year, a number of changes took place in the observatory to improve some technical characteristics and to upgrade some units to their required status. The report provides an overview of current geodetic VLBI activities and gives an outlook for the future.

  12. Volcanoes: Coming Up from Under.

    Science.gov (United States)

    Science and Children, 1980

    1980-01-01

    Provides specific information about the eruption of Mt. St. Helens in March 1980. Also discusses how volcanoes are formed and how they are monitored. Words associated with volcanoes are listed and defined. (CS)

  13. Synthesis of carboxyl-capped and bright YVO{sub 4}:Eu,Bi nanoparticles and their applications in immunochromatographic test strip assay

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Min; Sun, Tian-Ying; Wang, Jia-Hong; Yang, Peng; Gan, Liang; Liang, Li-Lei [Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Department of Physics, Wuhan University, Wuhan 430072 (China); Yu, Xue-Feng, E-mail: yxf@whu.edu.cn [Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Department of Physics, Wuhan University, Wuhan 430072 (China); Gong, Xing-Hou, E-mail: xinghoug@yahoo.com.cn [Department of Chemical and Environmental Engineering, Hubei University of Technology, Wuhan 430068 (China)

    2013-11-15

    Graphical abstract: - Highlights: • The morphology and properties of YVO{sub 4}:Eu,Bi nanoparticles were investigated. • YVO{sub 4}:Eu,Bi were coupled with IgG for bioprobes due to their good properties. • YVO{sub 4}:Eu,Bi were applied to immunochromatographic test strip assay. - Abstract: Carboxyl-capped YVO{sub 4}:Eu,Bi nanoparticles with average diameter of ∼10 nm were synthesized via a copolymer of phosphono and carboxylic acid mediated hydrothermal method. Under a 350 nm ultraviolet light excitation, the YVO{sub 4}:Eu,Bi NPs exhibit sharp and bright red emission peaked at 615 nm and with highest quantum yield of ∼43%. Furthermore, the nanoparticles show good water/buffer stability and feasible bioconjugation benefiting from the carboxylic groups on their surface. Based on these kind optical and surface properties of the YVO{sub 4}:Eu,Bi nanoparticles, an immunochromatographic test strip assay for quantitative determination of human IgG was achieved. This protocol can be extended to other rare-earth nanoparticles with the purpose of developing bioprobes for desired applications.

  14. The High Altitude Water Cherenkov Observatory

    CERN Document Server

    ,

    2013-01-01

    The High Altitude Water Cherenkov (HAWC) observatory is a large field of view, continuously operated, TeV gamma-ray experiment under construction at 4,100 m a.s.l. in Mexico. The HAWC observatory will have an order of magnitude better sensitivity, angular resolution, and background rejection than its predecessor, the Milagro experiment. The improved performance will allow us to detect both transient and steady emissions, to study the Galactic diffuse emission at TeV energies, and to measure or constrain the TeV spectra of GeV gamma-ray sources. In addition, HAWC will be the only ground-based instrument capable of detecting prompt emission from gamma-ray bursts above 50 GeV. The HAWC observatory will consist of an array of 300 water Cherenkov detectors (WCDs), each with four photomultiplier tubes. This array is currently under construction on the flanks of the Sierra Negra volcano near the city of Puebla, Mexico. The first thirty WCDs (forming an array approximately the size of Milagro) were deployed in Summer...

  15. Organizational changes at Earthquakes & Volcanoes

    Science.gov (United States)

    Gordon, David W.

    1992-01-01

    Primary responsibility for the preparation of Earthquakes & Volcanoes within the Geological Survey has shifted from the Office of Scientific Publications to the Office of Earthquakes, Volcanoes, and Engineering (OEVE). As a consequence of this reorganization, Henry Spall has stepepd down as Science Editor for Earthquakes & Volcanoes(E&V).

  16. Principal Component Analysis for pattern recognition in volcano seismic spectra

    Science.gov (United States)

    Unglert, Katharina; Jellinek, A. Mark

    2016-04-01

    Variations in the spectral content of volcano seismicity can relate to changes in volcanic activity. Low-frequency seismic signals often precede or accompany volcanic eruptions. However, they are commonly manually identified in spectra or spectrograms, and their definition in spectral space differs from one volcanic setting to the next. Increasingly long time series of monitoring data at volcano observatories require automated tools to facilitate rapid processing and aid with pattern identification related to impending eruptions. Furthermore, knowledge transfer between volcanic settings is difficult if the methods to identify and analyze the characteristics of seismic signals differ. To address these challenges we have developed a pattern recognition technique based on a combination of Principal Component Analysis and hierarchical clustering applied to volcano seismic spectra. This technique can be used to characterize the dominant spectral components of volcano seismicity without the need for any a priori knowledge of different signal classes. Preliminary results from applying our method to volcanic tremor from a range of volcanoes including K¯ı lauea, Okmok, Pavlof, and Redoubt suggest that spectral patterns from K¯ı lauea and Okmok are similar, whereas at Pavlof and Redoubt spectra have their own, distinct patterns.

  17. Machine Learning Method for Pattern Recognition in Volcano Seismic Spectra

    Science.gov (United States)

    Radic, V.; Unglert, K.; Jellinek, M.

    2016-12-01

    Variations in the spectral content of volcano seismicity related to changes in volcanic activity are commonly identified manually in spectrograms. However, long time series of monitoring data at volcano observatories require tools to facilitate automated and rapid processing. Techniques such as Self-Organizing Maps (SOM), Principal Component Analysis (PCA) and clustering methods can help to quickly and automatically identify important patterns related to impending eruptions. In this study we develop and evaluate an algorithm applied on a set of synthetic volcano seismic spectra as well as observed spectra from Kılauea Volcano, Hawai`i. Our goal is to retrieve a set of known spectral patterns that are associated with dominant phases of volcanic tremor before, during, and after periods of volcanic unrest. The algorithm is based on training a SOM on the spectra and then identifying local maxima and minima on the SOM 'topography'. The topography is derived from the first two PCA modes so that the maxima represent the SOM patterns that carry most of the variance in the spectra. Patterns identified in this way reproduce the known set of spectra. Our results show that, regardless of the level of white noise in the spectra, the algorithm can accurately reproduce the characteristic spectral patterns and their occurrence in time. The ability to rapidly classify spectra of volcano seismic data without prior knowledge of the character of the seismicity at a given volcanic system holds great potential for real time or near-real time applications, and thus ultimately for eruption forecasting.

  18. Sixth Harmonic of A Nd:YVO4 Laser Generation In KBBF for ARPES

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yong; LIU Guo-Dong; DONG Xiao-Li; ZHOU Xing-Jiang; WANG Gui-Ling; LI Cheng-Ming; PENG Qin-Jun; CUI Da-Fu; XU Zu-Yan; WANG Xiao-Yang; ZHU Yong; CHEN Chuang-Tian

    2008-01-01

    @@ We report that a deep ultraviolet (DUV)laser from the sixth harmonic of a 1064nm laser has been firstly used as light source in an ultrahigh energy-resolution angle-resolved photoemission spectroscopy(ARPES).The wavelength is 177.3nm obtained by using the second harmonic KBe2BO3F2 crystal with a frequency tripled 1064nm Nd:YVO4 laser.The large flux(1014-1015 photons/s)and narrow line width (0.26meV)are suitable for the ultrahigh-energy resolution ARPEs.The laser-ARPES can be a powerful tool to study the electronic structure at and near the Fermi level of the superconductor and correlated materials,The laser-ARPES has worked more than 500h already.

  19. Micromachining of glass by the third harmonic of nanosecond Nd:YVO 4 laser

    Science.gov (United States)

    Ramil, A.; Lamas, J.; Álvarez, J. C.; López, A. J.; Saavedra, E.; Yáñez, A.

    2009-03-01

    The ablation processing of glass was performed by using the third harmonic of nanosecond Nd:YVO 4 laser. The objective of this work was the formation of deep holes with a high aspect ratio in soda lime glass; with this purpose different ways to raster the glass surface with the focused laser beam, i.e., single line, parallel lines and orthogonally crossing lines, have been tried and the effect of different parameters as the number of lines and number of scans in the depth and inclination of the sidewalls of the hole has been analyzed. Moreover, to reduce the time consumption in the laser processing of glass plates the relationship between penetration depths and overlapping factor has been studied and an optimum value of scan speed has been obtained for a particular case.

  20. Experimental comparison of autodyne and heterodyne laser interferometry using a Nd:YVO4 microchip laser

    CERN Document Server

    Jacquin, Olivier; Glastre, Wilfried; Hugon, Olivier; De Chatellus, Hugues Guillet

    2012-01-01

    Using a Nd:YVO4 microchip laser with a relaxation frequency in the megahertz range, we have experimentally compared a heterodyne interferometer based on a Michelson configuration with an autodyne interferometer based on the laser optical feedback imaging (LOFI) method regarding their signal to noise ratios. In the heterodyne configuration, the beating between the reference beam and the signal beam is realized outside the laser cavity while in the autodyne configuration, the wave beating takes place inside the laser cavity and the relaxation oscillations of the laser intensity then play an important part. For a given laser output power, object under investigation and detection noise level, we have determined the amplification gain of the LOFI interferometer compared to the heterodyne interferometer. LOFI interferometry is demonstrated to show higher performances than heterodyne interferometry for a wide range of laser power and detection level of noise. The experimental results are in good agreement with the t...

  1. Hawaii's volcanoes revealed

    Science.gov (United States)

    Eakins, Barry W.; Robinson, Joel E.; Kanamatsu, Toshiya; Naka, Jiro; Smith, John R.; Takahashi, Eiichi; Clague, David A.

    2003-01-01

    Hawaiian volcanoes typically evolve in four stages as volcanism waxes and wanes: (1) early alkalic, when volcanism originates on the deep sea floor; (2) shield, when roughly 95 percent of a volcano's volume is emplaced; (3) post-shield alkalic, when small-volume eruptions build scattered cones that thinly cap the shield-stage lavas; and (4) rejuvenated, when lavas of distinct chemistry erupt following a lengthy period of erosion and volcanic quiescence. During the early alkalic and shield stages, two or more elongate rift zones may develop as flanks of the volcano separate. Mantle-derived magma rises through a vertical conduit and is temporarily stored in a shallow summit reservoir from which magma may erupt within the summit region or be injected laterally into the rift zones. The ongoing activity at Kilauea's Pu?u ?O?o cone that began in January 1983 is one such rift-zone eruption. The rift zones commonly extend deep underwater, producing submarine eruptions of bulbous pillow lava. Once a volcano has grown above sea level, subaerial eruptions produce lava flows of jagged, clinkery ?a?a or smooth, ropy pahoehoe. If the flows reach the ocean they are rapidly quenched by seawater and shatter, producing a steep blanket of unstable volcanic sediment that mantles the upper submarine slopes. Above sea level then, the volcanoes develop the classic shield profile of gentle lava-flow slopes, whereas below sea level slopes are substantially steeper. While the volcanoes grow rapidly during the shield stage, they may also collapse catastrophically, generating giant landslides and tsunami, or fail more gradually, forming slumps. Deformation and seismicity along Kilauea's south flank indicate that slumping is occurring there today. Loading of the underlying Pacific Plate by the growing volcanic edifices causes subsidence, forming deep basins at the base of the volcanoes. Once volcanism wanes and lava flows no longer reach the ocean, the volcano continues to submerge, while

  2. Facile synthesis, structural characterization, and photoluminescence mechanism of Dy{sup 3+} doped YVO{sub 4} and Ca{sup 2+} co-doped YVO{sub 4}:Dy{sup 3+} nano-lattices

    Energy Technology Data Exchange (ETDEWEB)

    Dhiren Meetei, Sanoujam, E-mail: sdmdhiren@gmail.com; Dorendrajit Singh, Shougaijam, E-mail: dorendrajit@yahoo.co.in, E-mail: mdebensingh@gmail.com [Department of Physics, Manipur University, Canchipur, Imphal-795003, Manipur (India); Deben Singh, Mutum, E-mail: dorendrajit@yahoo.co.in, E-mail: mdebensingh@gmail.com [Department of Physics, Thambal Marik College, Oinam-795134, Bishnupur, Manipur (India)

    2014-05-28

    Light plays a vital role in the evolution of life. From sunlight to candle-light and then to other form of lighting devices, human beings are utilizing light since time immemorial. Lighting devices such as conventional incandescent lamp and fluorescent lamp have been replaced by Light Emitting Diodes (LEDs) for the later is cheap, durable, etc. Now-a-days, phosphor converted LEDs have been burning issues in the fabrication of lighting devices. Especially, lanthanide ion(s) doped phosphors are of great interest for the same. However, doped phosphors have a limitation of luminescence quenching, i.e., instead of increasing luminescence on increasing dopant concentration, the luminescence decreases. Therefore, it must be rectified by one or other means so as to get maximum desirable intensity for uses in display or lighting devices. In the present work, YVO{sub 4}:Dy{sup 3+} and YVO{sub 4}:Dy{sup 3+}/Ca{sup 2+} nano-lattices are synthesized by a facile technique. Structural characterizations such as x-ray diffraction, SEM, TEM, HRTEM, and Selected Area Electron Diffraction (SAED) of the samples are reported. Photoluminescence (PL) excitation and emission, enhanced mechanism, and lifetime are thoroughly discussed. PL intensity of the quenched YVO{sub 4}:Dy{sup 3+} is made increased up to 432.63% by Ca{sup 2+} co-doping. Role of the Ca{sup 2+} on the luminescence enhanced mechanism of YVO{sub 4}:Dy{sup 3+}/Ca{sup 2+} is elucidated.

  3. Nd∶YVO4 Microchip Laser with a Plano/plano Cavity End-pumped by LD%LD抽运Nd∶YVO4的平-平腔微片激光器

    Institute of Scientific and Technical Information of China (English)

    马立苹; 胡鸿璋; 李增智; 孟宪林

    2000-01-01

    用一种简单方法实现了LD端面抽运Nd∶YVO4的平-平腔微片激光器,获得波长为1.064 μm的基横模(TEM00)输出.抽运阈值为40 mW,斜率效率为29.4%.简述了实验装置及结果.

  4. The added value of time-variable microgravimetry to the understanding of how volcanoes work

    Science.gov (United States)

    Carbone, Daniele; Poland, Michael; Greco, Filippo; Diament, Michel

    2017-01-01

    During the past few decades, time-variable volcano gravimetry has shown great potential for imaging subsurface processes at active volcanoes (including some processes that might otherwise remain “hidden”), especially when combined with other methods (e.g., ground deformation, seismicity, and gas emissions). By supplying information on changes in the distribution of bulk mass over time, gravimetry can provide information regarding processes such as magma accumulation in void space, gas segregation at shallow depths, and mechanisms driving volcanic uplift and subsidence. Despite its potential, time-variable volcano gravimetry is an underexploited method, not widely adopted by volcano researchers or observatories. The cost of instrumentation and the difficulty in using it under harsh environmental conditions is a significant impediment to the exploitation of gravimetry at many volcanoes. In addition, retrieving useful information from gravity changes in noisy volcanic environments is a major challenge. While these difficulties are not trivial, neither are they insurmountable; indeed, creative efforts in a variety of volcanic settings highlight the value of time-variable gravimetry for understanding hazards as well as revealing fundamental insights into how volcanoes work. Building on previous work, we provide a comprehensive review of time-variable volcano gravimetry, including discussions of instrumentation, modeling and analysis techniques, and case studies that emphasize what can be learned from campaign, continuous, and hybrid gravity observations. We are hopeful that this exploration of time-variable volcano gravimetry will excite more scientists about the potential of the method, spurring further application, development, and innovation.

  5. Boulder Magnetic Observatory

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are vector and scalar component values of the Earth's magnetic field for 2004 recorded at the Boulder Magnetic Observatory in Colorado. Vector values are...

  6. Global Health Observatory (GHO)

    Science.gov (United States)

    ... Data repository Reports Country statistics Map gallery Standards Global Health Observatory (GHO) data Monitoring health for the ... Health financing Health workforce 3.d National and global health risks International Health Regulations (2005) Monitoring Framework ...

  7. Technical-Information Products for a National Volcano Early Warning System

    Science.gov (United States)

    Guffanti, Marianne; Brantley, Steven R.; Cervelli, Peter F.; Nye, Christopher J.; Serafino, George N.; Siebert, Lee; Venezky, Dina Y.; Wald, Lisa

    2007-01-01

    Introduction Technical outreach - distinct from general-interest and K-12 educational outreach - for volcanic hazards is aimed at providing usable scientific information about potential or ongoing volcanic activity to public officials, businesses, and individuals in support of their response, preparedness, and mitigation efforts. Within the context of a National Volcano Early Warning System (NVEWS) (Ewert et al., 2005), technical outreach is a critical process, transferring the benefits of enhanced monitoring and hazards research to key constituents who have to initiate actions or make policy decisions to lessen the hazardous impact of volcanic activity. This report discusses recommendations of the Technical-Information Products Working Group convened in 2006 as part of the NVEWS planning process. The basic charge to the Working Group was to identify a web-based, volcanological 'product line' for NVEWS to meet the specific hazard-information needs of technical users. Members of the Working Group were: *Marianne Guffanti (Chair), USGS, Reston VA *Steve Brantley, USGS, Hawaiian Volcano Observatory HI *Peter Cervelli, USGS, Alaska Volcano Observatory, Anchorage AK *Chris Nye, Division of Geological and Geophysical Surveys and Alaska Volcano Observatory, Fairbanks AK *George Serafino, National Oceanic and Atmospheric Administration, Camp Springs MD *Lee Siebert, Smithsonian Institution, Washington DC *Dina Venezky, USGS, Volcano Hazards Team, Menlo Park CA *Lisa Wald, USGS, Earthquake Hazards Program, Golden CO

  8. Calculation of Spectroscopic Parameters of Ho3+ in Ho:YVO4 Crystal%Ho:YVO4晶体中Ho3+光谱参数的计算

    Institute of Scientific and Technical Information of China (English)

    杨文琴; 吴梅琴; 陈金铠; 庄健

    2001-01-01

    根据Ho3+在Ho:YVO4晶体的吸收谱和0.6~2.1 μm波段的荧光谱,用J-O理论计算了Ho3+的强度参数Ωλ,并由此计算了激发能级的振子强度、自发辐射跃迁几率、荧光分支比和积分发射截面等光谱参数,讨论了Ho:YVO4晶体作为红外激光材料的可能性。%The intensity parameters Ωλ of Ho3+ in Ho:YVO4 crystal were calculated with J-O theory according to the absorption spectrum.Based on these Ωλ values,the oscillator strength of excited energy state,spontaneous radiation rate,branching ratio and integrated emission cross section were estimated.A discussion on potentiality of application in the infrared laser material is given.

  9. Santa Maria Volcano, Guatemala

    Science.gov (United States)

    2002-01-01

    The eruption of Santa Maria volcano in 1902 was one of the largest eruptions of the 20th century, forming a large crater on the mountain's southwest flank. Since 1922, a lava-dome complex, Santiaguito, has been forming in the 1902 crater. Growth of the dome has produced pyroclastic flows as recently as the 2001-they can be identified in this image. The city of Quezaltenango (approximately 90,000 people in 1989) sits below the 3772 m summit. The volcano is considered dangerous because of the possibility of a dome collapse such as one that occurred in 1929, which killed about 5000 people. A second hazard results from the flow of volcanic debris into rivers south of Santiaguito, which can lead to catastrophic flooding and mud flows. More information on this volcano can be found at web sites maintained by the Smithsonian Institution, Volcano World, and Michigan Tech University. ISS004-ESC-7999 was taken 17 February 2002 from the International Space Station using a digital camera. The image is provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Searching and viewing of additional images taken by astronauts and cosmonauts is available at the NASA-JSC Gateway to

  10. Anatomy of a volcano

    NARCIS (Netherlands)

    Wassink, J.

    2011-01-01

    The Icelandic volcano Eyjafjallajökull caused major disruption in European airspace last year. According to his co-author, Freysteinn Sigmundsson, the reconstruction published in Nature six months later by aerospace engineering researcher, Dr Andy Hooper, opens up a new direction in volcanology. “W

  11. Royal Observatory, Greenwich

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    The Royal Observatory at Greenwich, London, founded in 1675, is the location of the Airy Transit Telescope that defines the prime meridian of the world and is the home of the Harrison Chronometers. The Observatory was founded by Charles II with the ultimate purpose of providing an accurate star catalog and model of the Moon's motion, that enabled mariners to find their longitude. During the twen...

  12. The Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Hojvat, C.

    1997-03-01

    The Pierre Auger Observatory is an international collaboration for the detailed study of the highest energy cosmic rays. It will operate at two similar sites, one in the northern hemisphere and one in the southern hemisphere. The Observatory is designed to collect a statistically significant data set of events with energies greater than 10{sup 19} eV and with equal exposures for the northern and southern skies.

  13. Dual-wavelength eye-safe Nd:GYSGG/YVO4 intracavity Raman laser under in-band pumping

    Science.gov (United States)

    Jiang, P. B.; Sheng, Q.; Ding, X.; Sun, B.; Liu, J.; Zhao, C.; Zhang, G. Z.; Yu, X. Y.; Li, B.; Wu, L.; Yao, J. Q.

    2017-01-01

    An acousto-optic (AO) Q-switched dual-wavelength laser operating at 1.5 μm eye-safe region is demonstrated via stimulated Raman scatting of a-cut YVO4-Nd:YVO4 crystal within an end-pumped dual-wavelength Nd:GYSGG laser cavity. The in-band pumping absorption peak and coefficient of the dual-wavelength laser crystal Nd:GYSGG are measured in order to carry out efficient pumping, thus overcoming the drawbacks of short thermal focal length of the crystal and scale up the eye-safe output. Under 23.2 W absorbed pump power, 2.11 W of simultaneous dual-wavelength outputs at 1497 and 1516 nm are obtained with a pulse repetition rate of 23 kHz and a corresponding conversion efficiency of 9.1%.

  14. The characteristics of Kerr-lens mode-locked self-Raman Nd:YVO4 1176 nm laser

    Science.gov (United States)

    Li, Zuohan; Peng, Jiying; Yao, Jianquan; Han, Ming

    2017-03-01

    In this paper we report on a compact and feasible dual-concave cavity CW Kerr-lens mode-locked self-Raman Nd:YVO4 laser. A self-starting diode-pumped picosecond Nd:YVO4 1176 nm laser is demonstrated without any additional components, where the stimulated Stokes Raman scattering and Kerr-lens-induced mode locking are operated in the same crystal. With an incident pump power of 12 W, the average output power at 1176 nm is up to 643 mW. Meanwhile, the repetition rate and the pulse width of the fundamental laser are measured to be 1.53 GHz and 8.6 ps, respectively. In addition, the yellow laser output at 588 nm is realized by frequency doubling with a LiB3O5 crystal.

  15. Suppressing the preferential σ-polarization oscillation in a high power Nd∶YVO4 laser with wedge laser crystal

    Institute of Scientific and Technical Information of China (English)

    Zheng Yao-Hui; Zhou Hai-Jun; Wang Ya-Jun; Wu Zhi-Qiang

    2013-01-01

    We observe the phenomenon of priority oscillation of the unexpected σ-polarization in high-power Nd∶YVO4 ring laser.The severe thermal lens of the σ-polarized lasing,compared with the π-polarized lasing,is the only reason for the phenomenon.By designing a wedge Nd∶YVO4 crystal as the gain medium,the unexpected σ-polarization is completely suppressed in the entire range of pump powers,and the polarization stability of the expected π-polarized output is enhanced.With the output power increasing from threshold to the maximum power,no σ-polarization lasing is observed.As a result,25.3 W of stable single-frequency laser output at 532 nm is experimentally demonstrated.

  16. 300 W laser-diode dual-end-pumped Nd:YVO4 Innoslab laser

    Science.gov (United States)

    Duan, Yabo; Song, Chengtian; Mao, Yefei

    2016-09-01

    We demonstrate a continuous wave neodymium-doped vanadate (Nd:YVO4) experiment with the laser diode dual end pumped directly in the band at 880 nm. Due to the advantage of the Innoslab laser, a 22 mm  ×  10 mm  ×  1 mm Nd:YVO4 crystal was used. By using a positive confocal unstable-stable hybrid fold resonator, a maximum power of 330 W was obtained at the absorbed pump power of 725 W. The corresponding optical-to-optical efficiency and slope efficiency were 45.5% and 55.8%, respectively. At an output power of 300 W, the beam quality factors M 2 in the unstable direction and stable direction were 1.7 and 2.1, respectively.

  17. Compact Continuous-Wave Nd:YVO4 Laser with Self-Raman Conversion and Sum Frequency Generation

    Institute of Scientific and Technical Information of China (English)

    ZHU Hai-Yong; ZHANG Ge; DUAN Yan-Min; HUANG Cheng-Hui; WEI Yong

    2011-01-01

    @@ Low threshold and compact cw Nd:YVO4 self-Raman lasers at 1176 nm and sum-frequency mixing of fundamental and first-Stokes wavelengths are demonstrated.A 20-mm Nd:YVO4 crystal is adopted in a compact plane-concave resonator.The results show that the cw Raman conversion is sensitive to cavity length.At an incident pump power of 22.5 W,output power of 1.53 W at 1175.6 nm is achieved,corresponding to the threshold of only 0.8 W and the slop efficiency of 8.1%.Intra-cavity sum-frequency generation is realized in a type-Ⅱ phase-matching cut KTP crystal,480 m W at 558.6 nm is obtained at incident pump power of 12 W.%Low threshold and compact cw Nd:YVO4 self-Ranman lasers at 11 76 nm and sum-frequency mixing of fundamental and first-Stokes wavelengths are demonstrated. A 20-mm Nd:YVO4 crystal is adopted in a compact plane-concave resonator. The results show that the cw Raman conversion is sensitive to cavity length. At an incident pump power of 22.5 W, output power of 153 W at 1175.6nm is achieved, corresponding to the threshold of only 0.8 W and the slop effciency of 8. 1% Intra-cavity sum- frequency generation is realized in a type-Ⅱ phase-matching cut KTP Crystal, 480mW at 558.6nm is obtained at incident pump power of 12 W.

  18. Integrating ALOS-2 and Sentinel-1 InSAR data for systematic volcano deformation monitoring

    Science.gov (United States)

    Hickey, James; Biggs, Juliet; Ebmeier, Susanna; Parker, Amy

    2016-04-01

    The recent launches of the Sentinel-1 and ALOS-2 satellites provide a wealth of new Interferometric Synthetic Aperture Radar (InSAR) data for Earth observation purposes. We exploit these data for volcano deformation monitoring with a particular focus on Latin America, which is nominated as a priority target area under the Committee on Earth Observation Satellites volcano pilot program. By conducting an integrated survey that employs both Sentinel-1 and ALOS-2 we are able to achieve previously unprecedented levels of spatial and temporal resolution and combat decorrelation arising from vegetation cover. Latin America is an ideal target region as it has a diversity of geographic volcano locations (e.g., dense rainforest to high-altitude deserts), as well as abundant and varied volcanic activity. The numerous local volcano observatories can also directly benefit from this additional InSAR data when integrating it alongside ground-based observations. To further facilitate this impact we are directing our data outputs to a global volcano deformation database in near-real-time to provide a first-order access point for observatory staff and research scientists in need of satellite-derived ground-deformation results. We will draw upon a selection of case studies within Latin America to demonstrate our approach and how it can enhance volcano monitoring and eruption forecasting efforts.

  19. Converting Y(OH){sub 3} nanofiber bundles to YVO{sub 4} polyhedrons for photodegradation of dye contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Li, Li [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); School of Chemical Engineering and Materials Engineering, Huainan Normal University, Huainan 232038 (China); Zou, Lei; Wang, Haoran [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Wang, Xiong, E-mail: xiongwang@njust.edu.cn [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2015-08-15

    Highlights: • YVO{sub 4} polyhedrons were prepared from Y(OH){sub 3} nanofiber bundles through a hydrothermal conversion process. • In contrast to the bulk oxide, the photocatalytic performance of the polyhedrons was much improved. • The main active species involved in photocatalytic oxidative reaction were also investigated. - Abstract: This paper reports a hydrothermal conversion process of rare earth microstructures, Y(OH){sub 3} nanofiber bundles, into YVO{sub 4} polyhedrons, together with the investigation on the related photocatalytic properties. The as-synthesized samples were characterized by a variety of techniques, including XRD, SEM, TEM and UV–vis diffuse reflectance spectroscopy. The photocatalytic activities of YVO{sub 4} polyhedrons were comparatively evaluated by the photodegradation of Rhodamine B and methylene blue. In contrast to the bulk oxide, the photocatalytic performance of the polyhedrons was much improved. The mechanism and the main active species involved in photocatalytic oxidative reaction were also investigated through the carriers trapping experiments.

  20. Self-Raman Nd:YVO4 laser and electro-optic technology for space-based sodium lidar instrument

    Science.gov (United States)

    Krainak, Michael A.; Yu, Anthony W.; Janches, Diego; Jones, Sarah L.; Blagojevic, Branimir; Chen, Jeffrey

    2014-02-01

    We are developing a laser and electro-optic technology to remotely measure Sodium (Na) by adapting existing lidar technology with space flight heritage. The developed instrumentation will serve as the core for the planning of an Heliophysics mission targeted to study the composition and dynamics of Earth's mesosphere based on a spaceborne lidar that will measure the mesospheric Na layer. We present performance results from our diode-pumped tunable Q-switched self-Raman c-cut Nd:YVO4 laser with intra-cavity frequency doubling that produces multi-watt 589 nm wavelength output. The c-cut Nd:YVO4 laser has a fundamental wavelength that is tunable from 1063-1067 nm. A CW External Cavity diode laser is used as a injection seeder to provide single-frequency grating tunable output around 1066 nm. The injection-seeded self-Raman shifted Nd:VO4 laser is tuned across the sodium vapor D2 line at 589 nm. We will review technologies that provide strong leverage for the sodium lidar laser system with strong heritage from the Ice Cloud and Land Elevation Satellite-2 (ICESat-2) Advanced Topographic Laser Altimeter System (ATLAS). These include a space-qualified frequency-doubled 9W @ 532 nm wavelength Nd:YVO4 laser, a tandem interference filter temperature-stabilized fused-silica-etalon receiver and high-bandwidth photon-counting detectors.

  1. Self-Raman Nd:YVO4 Laser and Electro-Optic Technology for Space-Based Sodium Lidar Instrument

    Science.gov (United States)

    Krainak, Michael A.; Yu, Anthony W.; Janches, Diego; Jones, Sarah L.; Blagojevic, Branimir; Chen, Jeffrey

    2014-01-01

    We are developing a laser and electro-optic technology to remotely measure Sodium (Na) by adapting existing lidar technology with space flight heritage. The developed instrumentation will serve as the core for the planning of an Heliophysics mission targeted to study the composition and dynamics of Earth's mesosphere based on a spaceborne lidar that will measure the mesospheric Na layer. We present performance results from our diode-pumped tunable Q-switched self-Raman c-cut Nd:YVO4 laser with intra-cavity frequency doubling that produces multi-watt 589 nm wavelength output. The c-cut Nd:YVO4 laser has a fundamental wavelength that is tunable from 1063-1067 nanometers. A CW (Continuous Wave) External Cavity diode laser is used as a injection seeder to provide single-frequency grating tunable output around 1066 nanometers. The injection-seeded self-Raman shifted Nd:VO4 laser is tuned across the sodium vapor D2 line at 589 nanometers. We will review technologies that provide strong leverage for the sodium lidar laser system with strong heritage from the Ice Cloud and Land Elevation Satellite-2 (ICESat-2) Advanced Topographic Laser Altimeter System (ATLAS). These include a space-qualified frequency-doubled 9 watts-at-532-nanometer wavelength Nd:YVO4 laser, a tandem interference filter temperature-stabilized fused-silica-etalon receiver and high-bandwidth photon-counting detectors.

  2. Strategies for the implementation of a European Volcano Observations Research Infrastructure

    Science.gov (United States)

    Puglisi, Giuseppe

    2015-04-01

    Active volcanic areas in Europe constitute a direct threat to millions of people on both the continent and adjacent islands. Furthermore, eruptions of "European" volcanoes in overseas territories, such as in the West Indies, an in the Indian and Pacific oceans, can have a much broader impacts, outside Europe. Volcano Observatories (VO), which undertake volcano monitoring under governmental mandate and Volcanological Research Institutions (VRI; such as university departments, laboratories, etc.) manage networks on European volcanoes consisting of thousands of stations or sites where volcanological parameters are either continuously or periodically measured. These sites are equipped with instruments for geophysical (seismic, geodetic, gravimetric, electromagnetic), geochemical (volcanic plumes, fumaroles, groundwater, rivers, soils), environmental observations (e.g. meteorological and air quality parameters), including prototype deployment. VOs and VRIs also operate laboratories for sample analysis (rocks, gases, isotopes, etc.), near-real time analysis of space-borne data (SAR, thermal imagery, SO2 and ash), as well as high-performance computing centres; all providing high-quality information on the current status of European volcanoes and the geodynamic background of the surrounding areas. This large and high-quality deployment of monitoring systems, focused on a specific geophysical target (volcanoes), together with the wide volcanological phenomena of European volcanoes (which cover all the known volcano types) represent a unique opportunity to fundamentally improve the knowledge base of volcano behaviour. The existing arrangement of national infrastructures (i.e. VO and VRI) appears to be too fragmented to be considered as a unique distributed infrastructure. Therefore, the main effort planned in the framework of the EPOS-PP proposal is focused on the creation of services aimed at providing an improved and more efficient access to the volcanological facilities

  3. Creating Griffith Observatory

    Science.gov (United States)

    Cook, Anthony

    2013-01-01

    Griffith Observatory has been the iconic symbol of the sky for southern California since it began its public mission on May 15, 1935. While the Observatory is widely known as being the gift of Col. Griffith J. Griffith (1850-1919), the story of how Griffith’s gift became reality involves many of the people better known for other contributions that made Los Angeles area an important center of astrophysics in the 20th century. Griffith began drawing up his plans for an observatory and science museum for the people of Los Angeles after looking at Saturn through the newly completed 60-inch reflector on Mt. Wilson. He realized the social impact that viewing the heavens could have if made freely available, and discussing the idea of a public observatory with Mt. Wilson Observatory’s founder, George Ellery Hale, and Director, Walter Adams. This resulted, in 1916, in a will specifying many of the features of Griffith Observatory, and establishing a committee managed trust fund to build it. Astronomy popularizer Mars Baumgardt convinced the committee at the Zeiss Planetarium projector would be appropriate for Griffith’s project after the planetarium was introduced in Germany in 1923. In 1930, the trust committee judged funds to be sufficient to start work on creating Griffith Observatory, and letters from the Committee requesting help in realizing the project were sent to Hale, Adams, Robert Millikan, and other area experts then engaged in creating the 200-inch telescope eventually destined for Palomar Mountain. A Scientific Advisory Committee, headed by Millikan, recommended that Caltech Physicist Edward Kurth be put in charge of building and exhibit design. Kurth, in turn, sought help from artist Russell Porter. The architecture firm of John C. Austin and Fredrick Ashley was selected to design the project, and they adopted the designs of Porter and Kurth. Philip Fox of the Adler Planetarium was enlisted to manage the completion of the Observatory and become its

  4. Volcano-hazard zonation for San Vicente volcano, El Salvador

    Science.gov (United States)

    Major, J.J.; Schilling, S.P.; Pullinger, C.R.; Escobar, C.D.; Howell, M.M.

    2001-01-01

    San Vicente volcano, also known as Chichontepec, is one of many volcanoes along the volcanic arc in El Salvador. This composite volcano, located about 50 kilometers east of the capital city San Salvador, has a volume of about 130 cubic kilometers, rises to an altitude of about 2180 meters, and towers above major communities such as San Vicente, Tepetitan, Guadalupe, Zacatecoluca, and Tecoluca. In addition to the larger communities that surround the volcano, several smaller communities and coffee plantations are located on or around the flanks of the volcano, and major transportation routes are located near the lowermost southern and eastern flanks of the volcano. The population density and proximity around San Vicente volcano, as well as the proximity of major transportation routes, increase the risk that even small landslides or eruptions, likely to occur again, can have serious societal consequences. The eruptive history of San Vicente volcano is not well known, and there is no definitive record of historical eruptive activity. The last significant eruption occurred more than 1700 years ago, and perhaps long before permanent human habitation of the area. Nevertheless, this volcano has a very long history of repeated, and sometimes violent, eruptions, and at least once a large section of the volcano collapsed in a massive landslide. The oldest rocks associated with a volcanic center at San Vicente are more than 2 million years old. The volcano is composed of remnants of multiple eruptive centers that have migrated roughly eastward with time. Future eruptions of this volcano will pose substantial risk to surrounding communities.

  5. Catalog of earthquake hypocenters at Alaskan volcanoes: January 1 through December 31, 2012

    Science.gov (United States)

    Dixon, James P.; Stihler, Scott D.; Power, John A.; Haney, Matthew M.; Parker, Tom; Searcy, Cheryl; Prejean, Stephanie

    2013-01-01

    Between January 1 and December 31, 2012, the Alaska Volcano Observatory located 4,787 earthquakes, of which 4,211 occurred within 20 kilometers of the 33 volcanoes monitored by a seismograph network. There was significant seismic activity at Iliamna, Kanaga, and Little Sitkin volcanoes in 2012. Instrumentation highlights for this year include the implementation of the Advanced National Seismic System Quake Monitoring System hardware and software in February 2012 and the continuation of the American Recovery and Reinvestment Act work in the summer of 2012. The operational highlight was the removal of Mount Wrangell from the list of monitored volcanoes. This catalog includes hypocenters, magnitudes, and statistics of the earthquakes located in 2012 with the station parameters, velocity models, and other files used to locate these earthquakes.

  6. Interactive Volcano Studies and Education Using Virtual Globes

    Science.gov (United States)

    Dehn, J.; Bailey, J. E.; Webley, P.

    2006-12-01

    Internet-based virtual globe programs such as Google Earth provide a spatial context for visualization of monitoring and geophysical data sets. At the Alaska Volcano Observatory, Google Earth is being used to integrate satellite imagery, modeling of volcanic eruption clouds and seismic data sets to build new monitoring and reporting tools. However, one of the most useful information sources for environmental monitoring is under utilized. Local populations, who have lived near volcanoes for decades are perhaps one of the best gauges for changes in activity. Much of the history of the volcanoes is only recorded through local legend. By utilizing the high level of internet connectivity in Alaska, and the interest of secondary education in environmental science and monitoring, it is proposed to build a network of observation nodes around local schools in Alaska and along the Aleutian Chain. A series of interactive web pages with observations on a volcano's condition, be it glow at night, puffs of ash, discolored snow, earthquakes, sounds, and even current weather conditions can be recorded, and the users will be able to see their reports in near real time. The database will create a KMZ file on the fly for upload into the virtual globe software. Past observations and legends could be entered to help put a volcano's long-term activity in perspective. Beyond the benefit to researchers and emergency managers, students and teachers in the rural areas will be involved in volcano monitoring, and gain an understanding of the processes and hazard mitigation efforts in their community. K-12 students will be exposed to the science, and encouraged to participate in projects at the university. Infrastructure at the university can be used by local teachers to augment their science programs, hopefully encouraging students to continue their education at the university level.

  7. Geology of Kilauea volcano

    Energy Technology Data Exchange (ETDEWEB)

    Moore, R.B. (Geological Survey, Denver, CO (United States). Federal Center); Trusdell, F.A. (Geological Survey, Hawaii National Park, HI (United States). Hawaiian Volcano Observatory)

    1993-08-01

    This paper summarizes studies of the structure, stratigraphy, petrology, drill holes, eruption frequency, and volcanic and seismic hazards of Kilauea volcano. All the volcano is discussed, but the focus is on its lower east rift zone (LERZ) because active exploration for geothermal energy is concentrated in that area. Kilauea probably has several separate hydrothermal-convection systems that develop in response to the dynamic behavior of the volcano and the influx of abundant meteoric water. Important features of some of these hydrothermal-convection systems are known through studies of surface geology and drill holes. Observations of eruptions during the past two centuries, detailed geologic mapping, radiocarbon dating, and paleomagnetic secular-variation studies indicate that Kilauea has erupted frequently from its summit and two radial rift zones during Quaternary time. Petrologic studies have established that Kilauea erupts only tholeiitic basalt. Extensive ash deposits at Kilauea's summit and on its LERZ record locally violent, but temporary, disruptions of local hydrothermal-convection systems during the interaction of water or steam with magma. Recent drill holes on the LERZ provide data on the temperatures of the hydrothermal-convection systems, intensity of dike intrusion, porosity and permeability, and an increasing amount of hydrothermal alteration with depth. The prehistoric and historic record of volcanic and seismic activity indicates that magma will continue to be supplied to deep and shallow reservoirs beneath Kilauea's summit and rift zones and that the volcano will be affected by eruptions and earthquakes for many thousands of years. 71 refs., 2 figs.

  8. 4D volcano gravimetry

    Science.gov (United States)

    Battaglia, Maurizio; Gottsmann, J.; Carbone, D.; Fernandez, J.

    2008-01-01

    Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. The ability of gravity measurements to detect subsurface mass flow is greatly enhanced if gravity measurements are analyzed and modeled with ground-deformation data. Obtaining the maximum information from microgravity studies requires careful evaluation of the layout of network benchmarks, the gravity environmental signal, and the coupling between gravity changes and crustal deformation. When changes in the system under study are fast (hours to weeks), as in hydrothermal systems and restless volcanoes, continuous gravity observations at selected sites can help to capture many details of the dynamics of the intrusive sources. Despite the instrumental effects, mainly caused by atmospheric temperature, results from monitoring at Mt. Etna volcano show that continuous measurements are a powerful tool for monitoring and studying volcanoes.Several analytical and numerical mathematical models can beused to fit gravity and deformation data. Analytical models offer a closed-form description of the volcanic source. In principle, this allows one to readily infer the relative importance of the source parameters. In active volcanic sites such as Long Valley caldera (California, U.S.A.) and Campi Flegrei (Italy), careful use of analytical models and high-quality data sets has produced good results. However, the simplifications that make analytical models tractable might result in misleading volcanological inter-pretations, particularly when the real crust surrounding the source is far from the homogeneous/ isotropic assumption. Using numerical models allows consideration of more realistic descriptions of the sources and of the crust where they are located (e.g., vertical and lateral mechanical discontinuities, complex source geometries, and topography). Applications at Teide volcano (Tenerife) and Campi Flegrei demonstrate the

  9. Pulsar virtual observatory

    CERN Document Server

    Keith, M; Lyne, A; Brooke, J

    2007-01-01

    The Pulsar Virtual Observatory will provide a means for scientists in all fields to access and analyze the large data sets stored in pulsar surveys without specific knowledge about the data or the processing mechanisms. This is achieved by moving the data and processing tools to a grid resource where the details of the processing are seen by the users as abstract tasks. By developing intelligent scheduling middle-ware the issues of interconnecting tasks and allocating resources are removed from the user domain. This opens up large sets of radio time-series data to a wider audience, enabling greater cross field astronomy, in line with the virtual observatory concept. Implementation of the Pulsar Virtual Observatory is underway, utilising the UK National Grid Service as the principal grid resource.

  10. Mexican Virtual Solar Observatory

    Science.gov (United States)

    Santillan, A.; Hernandez-Cervantes, L.; Gonzalez-Ponce, A.; Hill, F.; Blanco-Cano, X.

    2007-12-01

    The Virtual Solar Observatory (VSO) concept contains software tools for searching, manipulating, and analyzing data from archives of solar data at many different observatories around the world (Hill 2000). The VSO not only provides fast and reliable access to the existing solar data, but also represents a powerful and unique machinery to perform numerical simulations for the evolution of a variety of different phenomena associated with solar activity. Two Mexican Universities, Universidad Nacional Autónoma de México and the Universidad de Sonora, are working together to create the Mexican Virtual Solar Observatory (MVSO) that will be part of a wider National effort. In this work we present a general description of the MVSO project, as well as the advances obtained in the development of Graphical User Interfaces (GUI) to Remotely Perform Numerical Simulation of the Evolution of Coronal Mass Ejection in the Interplanetary Medium.

  11. The Collaborative Heliophysics Observatory

    Science.gov (United States)

    Hurlburt, N.; Freeland, S.; Cheung, M.; Bose, P.

    2007-12-01

    The Collaborative Heliophysics Observatory (CHO) would provide a robust framework and enabling tools to fully utilize the VOs for scientific discovery and collaboration. Scientists across the realm of heliophysics would be able to create, use and share applications -- either as services using familiar tools or through intuitive workflows -- that orchestrate access to data across all virtual observatories. These applications can be shared freely knowing that proper recognition of data and processing components are acknowledged; that erroneous use of data is flagged; and that results from the analysis runs will in themselves be shared Ð all in a transparent and automatic fashion. In addition, the CHO would incorporate cross-VO models and tools to weave the various virtual observatories into a unified system. These provide starting points for interactions across the solar/heliospheric and heliospheric/magnetospheric boundaries.

  12. Pairing the Volcano

    CERN Document Server

    Ionica, Sorina

    2011-01-01

    Isogeny volcanoes are graphs whose vertices are elliptic curves and whose edges are $\\ell$-isogenies. Algorithms allowing to travel on these graphs were developed by Kohel in his thesis (1996) and later on, by Fouquet and Morain (2001). However, up to now, no method was known, to predict, before taking a step on the volcano, the direction of this step. Hence, in Kohel's and Fouquet-Morain algorithms, many steps are taken before choosing the right direction. In particular, ascending or horizontal isogenies are usually found using a trial-and-error approach. In this paper, we propose an alternative method that efficiently finds all points $P$ of order $\\ell$ such that the subgroup generated by $P$ is the kernel of an horizontal or an ascending isogeny. In many cases, our method is faster than previous methods. This is an extended version of a paper published in the proceedings of ANTS 2010. In addition, we treat the case of 2-isogeny volcanoes and we derive from the group structure of the curve and the pairing ...

  13. The Sudbury Neutrino Observatory

    Science.gov (United States)

    Boger, J.; Hahn, R. L.; Rowley, J. K.; Carter, A. L.; Hollebone, B.; Kessler, D.; Blevis, I.; Dalnoki-Veress, F.; DeKok, A.; Farine, J.; Grant, D. R.; Hargrove, C. K.; Laberge, G.; Levine, I.; McFarlane, K.; Mes, H.; Noble, A. T.; Novikov, V. M.; O'Neill, M.; Shatkay, M.; Shewchuk, C.; Sinclair, D.; Clifford, E. T. H.; Deal, R.; Earle, E. D.; Gaudette, E.; Milton, G.; Sur, B.; Bigu, J.; Cowan, J. H. M.; Cluff, D. L.; Hallman, E. D.; Haq, R. U.; Hewett, J.; Hykawy, J. G.; Jonkmans, G.; Michaud, R.; Roberge, A.; Roberts, J.; Saettler, E.; Schwendener, M. H.; Seifert, H.; Sweezey, D.; Tafirout, R.; Virtue, C. J.; Beck, D. N.; Chan, Y. D.; Chen, X.; Dragowsky, M. R.; Dycus, F. W.; Gonzalez, J.; Isaac, M. C. P.; Kajiyama, Y.; Koehler, G. W.; Lesko, K. T.; Moebus, M. C.; Norman, E. B.; Okada, C. E.; Poon, A. W. P.; Purgalis, P.; Schuelke, A.; Smith, A. R.; Stokstad, R. G.; Turner, S.; Zlimen, I.; Anaya, J. M.; Bowles, T. J.; Brice, S. J.; Esch, E.-I.; Fowler, M. M.; Goldschmidt, A.; Hime, A.; McGirt, A. F.; Miller, G. G.; Teasdale, W. A.; Wilhelmy, J. B.; Wouters, J. M.; Anglin, J. D.; Bercovitch, M.; Davidson, W. F.; Storey, R. S.; Biller, S.; Black, R. A.; Boardman, R. J.; Bowler, M. G.; Cameron, J.; Cleveland, B.; Ferraris, A. P.; Doucas, G.; Heron, H.; Howard, C.; Jelley, N. A.; Knox, A. B.; Lay, M.; Locke, W.; Lyon, J.; Majerus, S.; Moorhead, M.; Omori, M.; Tanner, N. W.; Taplin, R. K.; Thorman, M.; Wark, D. L.; West, N.; Barton, J. C.; Trent, P. T.; Kouzes, R.; Lowry, M. M.; Bell, A. L.; Bonvin, E.; Boulay, M.; Dayon, M.; Duncan, F.; Erhardt, L. S.; Evans, H. C.; Ewan, G. T.; Ford, R.; Hallin, A.; Hamer, A.; Hart, P. M.; Harvey, P. J.; Haslip, D.; Hearns, C. A. W.; Heaton, R.; Hepburn, J. D.; Jillings, C. J.; Korpach, E. P.; Lee, H. W.; Leslie, J. R.; Liu, M.-Q.; Mak, H. B.; McDonald, A. B.; MacArthur, J. D.; McLatchie, W.; Moffat, B. A.; Noel, S.; Radcliffe, T. J.; Robertson, B. C.; Skensved, P.; Stevenson, R. L.; Zhu, X.; Gil, S.; Heise, J.; Helmer, R. L.; Komar, R. J.; Nally, C. W.; Ng, H. S.; Waltham, C. E.; Allen, R. C.; Bühler, G.; Chen, H. H.; Aardsma, G.; Andersen, T.; Cameron, K.; Chon, M. C.; Hanson, R. H.; Jagam, P.; Karn, J.; Law, J.; Ollerhead, R. W.; Simpson, J. J.; Tagg, N.; Wang, J.-X.; Alexander, C.; Beier, E. W.; Cook, J. C.; Cowen, D. F.; Frank, E. D.; Frati, W.; Keener, P. T.; Klein, J. R.; Mayers, G.; McDonald, D. S.; Neubauer, M. S.; Newcomer, F. M.; Pearce, R. J.; de Water, R. G. V.; Berg, R. V.; Wittich, P.; Ahmad, Q. R.; Beck, J. M.; Browne, M. C.; Burritt, T. H.; Doe, P. J.; Duba, C. A.; Elliott, S. R.; Franklin, J. E.; Germani, J. V.; Green, P.; Hamian, A. A.; Heeger, K. M.; Howe, M.; Drees, R. M.; Myers, A.; Robertson, R. G. H.; Smith, M. W. E.; Steiger, T. D.; Wechel, T. V.; Wilkerson, J. F.

    2000-07-01

    The Sudbury Neutrino Observatory is a second-generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.

  14. The Sudbury Neutrino Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Boger, J.; Hahn, R.L.; Rowley, J.K.; Carter, A.L.; Hollebone, B.; Kessler, D.; Blevis, I.; Dalnoki-Veress, F.; DeKok, A.; Farine, J.; Grant, D.R.; Hargrove, C.K.; Laberge, G.; Levine, I.; McFarlane, K.; Mes, H.; Noble, A.T.; Novikov, V.M.; O' Neill, M.; Shatkay, M.; Shewchuk, C.; Sinclair, D.; Clifford, E.T.H.; Deal, R.; Earle, E.D.; Gaudette, E.; Milton, G.; Sur, B.; Bigu, J.; Cowan, J.H.M.; Cluff, D.L.; Hallman, E.D.; Haq, R.U.; Hewett, J.; Hykawy, J.G.; Jonkmans, G.; Michaud, R.; Roberge, A.; Roberts, J.; Saettler, E.; Schwendener, M.H.; Seifert, H.; Sweezey, D.; Tafirout, R.; Virtue, C.J.; Beck, D.N.; Chan, Y.D.; Chen, X.; Dragowsky, M.R.; Dycus, F.W.; Gonzalez, J.; Isaac, M.C.P.; Kajiyama, Y.; Koehler, G.W.; Lesko, K.T.; Moebus, M.C.; Norman, E.B.; Okada, C.E.; Poon, A.W.P.; Purgalis, P.; Schuelke, A.; Smith, A.R.; Stokstad, R.G.; Turner, S.; Zlimen, I.; Anaya, J.M.; Bowles, T.J.; Brice, S.J.; Esch, Ernst-Ingo; Fowler, M.M.; Goldschmidt, Azriel; Hime, A.; McGirt, A.F.; Miller, G.G.; Teasdale, W.A.; Wilhelmy, J.B.; Wouters, J.M.; Anglin, J.D.; Bercovitch, M.; Davidson, W.F.; Storey, R.S.; Biller, S.; Black, R.A.; Boardman, R.J.; Bowler, M.G.; Cameron, J.; Cleveland, B.; Ferraris, A.P.; Doucas, G.; Heron, H.; Howard, C.; Jelley, N.A. E-mail: N.Jelley1@physics.ox.ac.uk; Knox, A.B.; Lay, M.; Locke, W.; Lyon, J.; Majerus, S.; Moorhead, M.; Omori, M.; Tanner, N.W.; Taplin, R.K.; Thorman, M.; Wark, D.L.; West, N.; Barton, J.C.; Trent, P.T.; Kouzes, R.; Lowry, M.M.; Bell, A.L.; Bonvin, E.; Boulay, M.; Dayon, M.; Duncan, F.; Erhardt, L.S.; Evans, H.C.; Ewan, G.T.; Ford, R.; Hallin, A.; Hamer, A.; Hart, P.M.; Harvey, P.J.; Haslip, D.; Hearns, C.A.W.; Heaton, R.; Hepburn, J.D.; Jillings, C.J.; Korpach, E.P.; Lee, H.W.; Leslie, J.R.; Liu, M.-Q.; Mak, H.B.; McDonald, A.B.; MacArthur, J.D.; McLatchie, W.; Moffat, B.A.; Noel, S.; Radcliffe, T.J.; Robertson, B.C.; Skensved, P.; Stevenson, R.L.; Zhu, X.; Gil, S.; Heise, J.; Helmer, R.L.; Komar, R.J.; Nally, C.W. [and others

    2000-07-11

    The Sudbury Neutrino Observatory is a second-generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D{sub 2}O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.

  15. Arecibo Observatory for All

    Science.gov (United States)

    Isidro, Gloria M.; Pantoja, C. A.; Bartus, P.; La Rosa, C.

    2006-12-01

    We describe new materials available at Arecibo Observatory for visitors with visual impairments. These materials include a guide in Braille that describes the telescope, some basic terms used in radio astronomy and frequently asked questions. We have also designed a tactile model of the telescope. We are interested that blind visitors can participate of the excitement of the visit to the worlds largest radio telescope. We would like to thank the "Fundacion Comunitaria de Puerto Rico" for the scholarship that allowed GMI to work on this project. We would like to express our gratitude to the Arecibo Observatory/NAIC for their support.

  16. The Sudbury Neutrino Observatory

    CERN Document Server

    Boger, J; Rowley, J K; Carter, A L; Hollebone, B; Kessler, D; Blevis, I; Dalnoki-Veress, F; De Kok, A; Farine, J; Grant, D R; Hargrove, C K; Laberge, G; Levine, I; McFarlane, K W; Mes, H; Noble, A T; Novikov, V M; O'Neill, M; Shatkay, M; Shewchuk, C; Sinclair, D; Clifford, E T H; Deal, R; Earle, E D; Gaudette, E; Milton, G; Sur, B; Bigu, J; Cowan, J H M; Cluff, D L; Hallman, E D; Haq, R U; Hewett, J L; Hykawy, J G; Jonkmans, G; Michaud, R; Roberge, A; Roberts, J; Saettler, E; Schwendener, M H; Seifert, H; Sweezey, D; Tafirout, R; Virtue, C J; Beck, D N; Chan, Y D; Chen, X; Dragowsky, M R; Dycus, F W; González, J; Isaac, M C P; Kajiyama, Y; Köhler, G W; Lesko, K T; Moebus, M C; Norman, E B; Okada, C E; Poon, A W P; Purgalis, P; Schülke, A; Smith, A R; Stokstad, R G; Turner, S; Zlimen, I; Anaya, J M; Bowles, T J; Brice, S J; Esch, E I; Fowler, M M; Goldschmidt, A; Hime, A; McGirt, A F; Miller, G G; Teasdale, W A; Wilhelmy, J B; Wouters, J M; Anglin, J D; Bercovitch, M; Davidson, W F; Storey, R S; Biller, S; Black, R A; Boardman, R J; Bowler, M G; Cameron, J; Cleveland, B; Ferraris, A P; Doucas, G; Heron, H; Howard, C; Jelley, N A; Knox, A B; Lay, M; Locke, W; Lyon, J; Majerus, S; Moorhead, M E; Omori, Mamoru; Tanner, N W; Taplin, R K; Thorman, M; Wark, D L; West, N; Barton, J C; Trent, P T; Kouzes, R; Lowry, M M; Bell, A L; Bonvin, E; Boulay, M; Dayon, M; Duncan, F; Erhardt, L S; Evans, H C; Ewan, G T; Ford, R; Hallin, A; Hamer, A; Hart, P M; Harvey, P J; Haslip, D; Hearns, C A W; Heaton, R; Hepburn, J D; Jillings, C J; Korpach, E P; Lee, H W; Leslie, J R; Liu, M Q; Mak, H B; McDonald, A B; MacArthur, J D; McLatchie, W; Moffat, B A; Noel, S; Radcliffe, T J; Robertson, B C; Skensved, P; Stevenson, R L; Zhu, X; Gil, S; Heise, J; Helmer, R L; Komar, R J; Nally, C W; Ng, H S; Waltham, C E; Allen, R C; Buhler, G; Chen, H H; Aardsma, G; Andersen, T; Cameron, K; Chon, M C; Hanson, R H; Jagam, P; Karn, J; Law, J; Ollerhead, R W; Simpson, J J; Tagg, N; Wang, J X; Alexander, C; Beier, E W; Cook, J C; Cowen, D F; Frank, E D; Frati, W; Keener, P T; Klein, J R; Mayers, G; McDonald, D S; Neubauer, M S; Newcomer, F M; Pearce, R J; Van de Water, R G; Van Berg, R; Wittich, P; Ahmad, Q R; Beck, J M; Browne, M C; Burritt, T H; Doe, P J; Duba, C A; Elliott, S R; Franklin, J E; Germani, J V; Green, P; Hamian, A A; Heeger, K M; Howe, M; Meijer-Drees, R; Myers, A; Robertson, R G H; Smith, M W E; Steiger, T D; Van Wechel, T; Wilkerson, J F

    2000-01-01

    The Sudbury Neutrino Observatory is a second generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.

  17. Collaborative Monitoring and Hazard Mitigation at Fuego Volcano, Guatemala

    Science.gov (United States)

    Lyons, J. J.; Bluth, G. J.; Rose, W. I.; Patrick, M.; Johnson, J. B.; Stix, J.

    2007-05-01

    A portable, digital sensor network has been installed to closely monitor changing activity at Fuego volcano, which takes advantage of an international collaborative effort among Guatemala, U.S. and Canadian universities, and the Peace Corps. The goal of this effort is to improve the understanding shallow internal processes, and consequently to more effectively mitigate volcanic hazards. Fuego volcano has had more than 60 historical eruptions and nearly-continuous activity make it an ideal laboratory to study volcanic processes. Close monitoring is needed to identify base-line activity, and rapidly identify and disseminate changes in the activity which might threaten nearby communities. The sensor network is comprised of a miniature DOAS ultraviolet spectrometer fitted with a system for automated plume scans, a digital video camera, and two seismo-acoustic stations and portable dataloggers. These sensors are on loan from scientists who visited Fuego during short field seasons and donated use of their sensors to a resident Peace Corps Masters International student from Michigan Technological University for extended data collection. The sensor network is based around the local volcano observatory maintained by Instituto National de Sismologia, Vulcanologia, Metrologia e Hidrologia (INSIVUMEH). INSIVUMEH provides local support and historical knowledge of Fuego activity as well as a secure location for storage of scientific equipment, data processing, and charging of the batteries that power the sensors. The complete sensor network came online in mid-February 2007 and here we present preliminary results from concurrent gas, seismic, and acoustic monitoring of activity from Fuego volcano.

  18. Observatory of Shiraz University

    Science.gov (United States)

    Bordbar, G. H.; Bahrani, F.

    2016-12-01

    Here we write about the observatory of Shiraz University, which has the largest active telescope in Iran but now, because of problems like light pollution of the nearby city and exhaustion of its largest telescope we need a plan for modernization and automatization in a new place.

  19. Arecibo Observatory for All

    Science.gov (United States)

    Bartus, P.; Isidro, G. M.; La Rosa, C.; Pantoja, C. A.

    2007-01-01

    We describe new materials available at the Arecibo Observatory for visitors with visual impairments. These materials include a guide in Braille that describes the telescope, explains some basic terms used in radio astronomy, and lists frequently asked questions. We have also designed a tactile model of the telescope. Our interest is in enabling…

  20. In Brief: Underwater volcano gets real-time monitoring

    Science.gov (United States)

    Zielinski, Sarah

    2007-05-01

    A real-time underwater earthquake monitoring system was installed on the top of Kick'em Jenny, an underwater volcano located off the north coast of Grenada, on 6 May. The Real Time Offshore Seismic Station (RTOSS) consists of an ocean-bottom seismometer connected by a stretchy hose to a buoy on the ocean surface. The buoy is powered by solar panels and transmits seismic data by high-frequency radio to an observatory in Sauteurs, Grenada. The RTOSS research team, led by scientists from the Woods Hole Oceanographic Institution, is coordinating with the Grenadian National Disaster Management Agency and the Seismic Unit of the University of the West Indies to incorporate the RTOSS data into existing regional monitoring. Kick'em Jenny, the only `live' submarine volcano in the West Indies, last erupted in 2001.

  1. A facile single-step procedure for the synthesis of luminescent Ln{sup 3+}:YVO{sub 4} (Ln = Eu or Er + Yb)-silica nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ocana, Manuel, E-mail: mjurado@icmse.csic.es [Instituto de Ciencia de Materiales de Sevilla, CSIC-US, Americo Vespucio 49, 41092 Isla de la Cartuja, Sevilla (Spain); Cantelar, Eugenio; Cusso, Fernando [Depto. Fisica de Materiales, C-IV, Universidad Autonoma de Madrid (Spain)

    2011-01-01

    A simple and single-step method for the production of Ln-doped YVO{sub 4} nanocrystals and their simultaneous encapsulation in a silica network based on the pyrolysis of liquid aerosols at 800 deg. C is reported. The procedure is illustrated for Yb,Er:YVO{sub 4}-silica nanocomposites consisting of spherical particles, which present up-converted green luminescence after IR excitation whose efficiency increased on annealing up to 1000 deg. C due to the release of impurities (adsorbed water, and residual anions). XPS spectroscopy and TEM observations revealed that the surface of the composite particles was enriched in silica, which would facilitate their functionalisation required to use them in biological applications. The procedure can also be used to prepare other rare earth doped systems as illustrated for the case of Eu-doped YVO{sub 4}/silica having down-converted red luminescence.

  2. High power eye-safe Er3+:YVO4 laser diode-pumped at 976 nm and emitting at 1603 nm

    Science.gov (United States)

    Newburgh, G. A.; Dubinskii, M.

    2016-02-01

    We report on the performance of an eye-safe laser based on a Er:YVO4 single crystal, diode-pumped at 976 nm (4I15/2-->4I11/2 transition) and operating at 1603 nm (4I13/2-->4I15/2 transition) with good beam quality. A 10 mm long Er3+:YVO4 slab, cut with its c-axis perpendicular to the laser cavity axis, was pumped in σ-polarization and lased in π-polarization. The laser operated in a quasi-continuous wave (Q-CW) regime with nearly 9 W output power, and with a slope efficiency of about 39% with respect to absorbed power. This is believed to be the highest efficiency and highest power achieved from an Er3+:YVO4 laser pumped in the 970-980 nm absorption band.

  3. A passively Q-switched Ho:YVO4 Laser at 2.05 μm with Graphene Saturable Absorber

    Directory of Open Access Journals (Sweden)

    Wenmiao Lin

    2016-05-01

    Full Text Available We report a passively Q-switched Ho:YVO4 laser pumped at 1.94 µm with multilayer graphene as a saturable absorber. At the absorbed pump power of 9.3 W, the maximum average output power of 2.2 W was obtained in Ho:YVO4 laser with minimum pulse width of 265.2 ns and pulse repetition rate of 131.6 kHz at 2052.1 nm. In addition, a beam quality factor of M2~1.7 was measured at the maximum output level. This is, as far as we know, the first time that graphene has been used in a passively Q-switched Ho:YVO4 laser.

  4. Local-moment formation and metal–nonmetal transition in Ca1-YVO3 and Ca1-YTiO3

    Indian Academy of Sciences (India)

    Y Nishihara; H Kawanaka; H Bando

    2002-05-01

    Electron-doped metallic states of Ca1-YVO3 and Ca1-YTiO3 change into nonmetallic states around ∼ 0.4 and 0.6, respectively. The residual resistivity in the metallic states increases with increasing effective magnetic moment or coefficient of 2 term of resistivity. The effective moment reaches ∼ 0.5 B/molecule in Ca1-YVO3 and also in Ca1-YTiO3 near the metal–nonmetal phase boundary. In these metallic states, ∼ 10% of 3 atoms seem to have large localized magnetic moments. In electron-doped metallic sample of Ca1-YVO3, the temperature dependence of resistance shows no resistance-minimum. However, weak negative magneto-resistance is observed for the sample with = 0.2 up to 50 Tesla at 4.2 K.

  5. Bioactive coating on titanium implants modified by Nd:YVO{sub 4} laser

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Filho, Edson de, E-mail: edsonafilho@yahoo.com.br [Universidade Estadual Paulista - UNESP, Instituto de Quimica, Grupo de Biomateriais, Caixa Postal 355, 14800-900, Araraquara, SP (Brazil); Fraga, Alexandre F. [Universidade Federal de Sao Carlos - UFSCar- Departamento de Engenharia de Materiais-DEMa Rodovia Washington Luis, km 235 - SP-310 13565-905, Sao Carlos, SP (Brazil); Bini, Rafael A.; Guastaldi, Antonio C. [Universidade Estadual Paulista - UNESP, Instituto de Quimica, Grupo de Biomateriais, Caixa Postal 355, 14800-900, Araraquara, SP (Brazil)

    2011-03-01

    Apatite coating was applied on titanium surfaces modified by Nd:YVO{sub 4} laser ablations with different energy densities (fluency) at ambient pressure and atmosphere. The apatites were deposited by biomimetic method using a simulated body fluid solution that simulates the salt concentration of bodily fluids. The titanium surfaces submitted to the fast melting and solidification processes (ablation) were immersed in the simulated body fluid solution for four days. The samples were divided into two groups, one underwent heat treatment at 600 deg. C and the other dried at 37 deg. C. For the samples treated thermally the diffractograms showed the formation of a phase mixture, with the presence of the hydroxyapatite, tricalcium phosphate, calcium deficient hydroxyapatite, carbonated hydroxyapatite and octacalcium phosphate phases. For the samples dried only the formation of the octacalcium phosphate and hydroxyapatite phases was verified. The infrared spectra show bands relative to chemical bonds confirmed by the diffraction analyses. The coating of both the samples with and without heat treatment present dense morphology and made up of a clustering of spherical particles ranging from 5 to 20 {mu}m. Based on the results we infer that the modification of implant surfaces employing laser ablations leads to the formation of oxides that help the formation of hydroxyapatite without the need of a heat treatment.

  6. 888 nm pumped dual Nd:YVO4 crystals acousto-optic Q-switched laser

    Science.gov (United States)

    Zhang, Wenqi; Shen, Yijie; Meng, Yuan; Gong, Mali

    2017-10-01

    888 nm pumped acousto-optic (AO) Q-switched laser with high output power and high efficiency under dual Nd:YVO4 crystals configuration is firstly demonstrated and rate equations for dual-crystal lasers are further ameliorated and investigated. In continuous wave (CW) operation, we experimentally achieve a maximum output power exceeding 50 W. The global optical efficiency reaches 49.5% and the slope efficiency attains 55.5% via using a 1.5 at.% crystal with a 0.5 at.% crystal. In Q-switch operation, by utilizing double 0.5 at.% crystals, the global optical efficiency rises from 25.6% to 45.6% and the pulse duration varies from 26.2 to 42.4 ns when pulse repetition frequency (PRF) increases from 10 to 100 kHz. The measured beam quality factors M2 at 100 kHz are 1.012 and 1.041 with 52.8 W output power in the two orthogonal directions respectively.

  7. Intrinsic luminescence and energy transfer processes in pure and doped YVO{sub 4} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pankratov, V.; Grigorjeva, L.; Millers, D. [Institute of Solid State Physics, University of Latvia, Riga (Latvia); Yochum, H.M. [Department of Physics and Engineering, Sweet Briar College, VA (United States)

    2007-03-15

    Luminescence properties of nominally pure and neodymium doped YVO{sub 4} single crystals have been studied by means of time-resolved luminescence spectroscopy technique. It was detected that, besides the main well-known blue excitonic emission band near 2.8 eV, an additional UV emission band at {proportional_to}3.1 eV appears in the spectra of intrinsic luminescence at low temperatures ({proportional_to}80 K) for all crystals studied. Decay time of the UV band is much faster in comparison with the blue one and the UV band is quenched at temperatures above 150 K. Origin of the UV emission band is discussed. A significant rise front was observed in the relaxation kinetics of Nd{sup 3+} emission under band-to-band excitation. The time constant of the rise front of the Nd{sup 3+} emission is very close to decay time of the blue emission in a wide temperature range. It is suggested that the energy transfer process from the host lattice to neodymium ions occurs via excitonic states. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Fabrication of microlens arrays on soda-lima glasses with a Nd:YVO4laser

    Science.gov (United States)

    Nieto, Daniel; Flores-Arias, M. Teresa; O'Connor, Gerard M.; Gómez-Reino, Carlos

    2011-05-01

    We present a laser direct-write technique that is capable of providing microlens arrays on soda-lime glass substrate from one step ablation process, permitting one to shorten the typical times of microlens fabrication with other direct-writing techniques. The technique is based on the combination of a Q-switched Nd:YVO4 laser and a galvanometer system for addressing the output beam laser. The geometrical and optical parameters of the microlenses have been measured to characterize the microlens arrays produced on an area of 2 mm×2 mm. Focal length values around 118 μm have been obtained by measuring the sag and the diameter of the microlens with a confocal microscope (nondirect method) or directly, using a microscope objective with a CCD camera. The practicality of both methods is shown in the good agreement between the obtained results for the focal length of microlenses. By using a noncontact profilometer, the surface roughness of the microlens has been measured and compared with that of a glass substrate.

  9. Ablation of graphene film by direct Nd:YVO4 laser under various beaming conditions.

    Science.gov (United States)

    Lee, Jeongmin; Han, Jae-Hee; Lee, Jung-Hun; Yoo, Ji-Beom; Cho, Seongjae; Kwon, Sang Jik; Cho, Eou Sik

    2014-12-01

    Recently, graphene is gaining increasing popularity as one of the most functional materials for advanced electronic and optical devices owing to its high carrier mobility and optical transparency. Patterning the graphene calls for particular cares in line definition without carbon (C)-based residues that might be working as a leakage path. Thus, realization and processing of the graphene monolayer are very complicated and need to be stringently controlled. For this reason, in accordance, processing technology should be evolved with higher reliability and accuracy, and compatibility with the conventional unit processes including electron beam (e-beam) lithography, plasma etching, and nano-dimensional optical lithography. In this work, a reliable, simple, and cost-effective technique for patterning the graphene is proposed. Graphene film transferred on glass substrate is directly patterned by a quality factor (Q)-switched neodymium-doped yttrium vanadate (Nd:YVO4, λ = 1064 nm) pumped laser diode (LD). In order to optimize the process condition, various beaming conditions of repetition rate and scanning speed are experimented. From the optical microscope images, it has been shown that graphene film was more easily etched by direct laser patterning technique at higher repetition and faster scanning speed. It was confirmed by Raman spectrum where 2-dimensional (2-D) and graphite (G) peaks were closely investigated that graphene residue was also completely removed after the proposed processing technique.

  10. Effect of synthesis conditions and surrounding medium on luminescence properties of YVO4:Eu3+nanopowders

    Institute of Scientific and Technical Information of China (English)

    EV Golyeva; DV Tolstikova; IE Kolesnikov; MD Mikhailov

    2015-01-01

    Nanocrystalline yttrium vanadate doped with europium ions powders were synthesized via sol-gel method based on decomposition of metal-polymer complex. X-ray diffraction analysis showed that samples had pure tetragonal phase without any impurities. Scanning electron microscopy and static light scattering technique were used to study morphology and size of prepared nanoparticles. Average diameter of the nanoparticles was about 40 nm. The changes in structural and luminescence properties were observed as a function of the first and second calcination temperature. The optimal conditions for synthesis of nanoparticles were determined asТ1=500 °С, t1=1 h;Т2=950 °С, t2=1.5 h. The effect of different media surrounding the nanoparticles on their luminescence properties and lifetime was investigated and discussed in terms of effective refractive index. It was found that the observed lifetime of YVO4:Eu3+ 5 at.% nanophosphor was decreased from 0.64 ms in air (nmed=1) to 0.45 ms in chalcogenide glass As39S61 (nmed=2.39).

  11. Surface modification induced by UV nanosecond Nd:YVO4 laser structuring on biometals

    Science.gov (United States)

    Fiorucci, M. Paula; López, Ana J.; Ramil, Alberto

    2014-08-01

    Laser surface texturing is a promising tool for improving metallic biomaterials performance in dental and orthopedic bone-replacing applications. Laser ablation modifies the topography of bulk material and might alter surface properties that govern the interactions with the surrounding tissue. This paper presents a preliminary evaluation of surface modifications in two biometals, stainless steel 316L and titanium alloy Ti6Al4V by UV nanosecond Nd:YVO4. Scanning electron microscopy of the surface textured by parallel micro-grooves reveals a thin layer of remelted material along the grooves topography. Furthermore, X-ray diffraction allowed us to appreciate a grain refinement of original crystal structure and consequently induced residual strain. Changes in the surface chemistry were determined by means of X-ray photoelectron spectroscopy; in this sense, generalized surface oxidation was observed and characterization of the oxides and other compounds such hydroxyl groups was reported. In case of titanium alloy, oxide layer mainly composed by TiO2 which is a highly biocompatible compound was identified. Furthermore, laser treatment produces an increase in oxide thickness that could improve the corrosion behavior of the metal. Otherwise, laser treatment led to the formation of secondary phases which might be detrimental to physical and biocompatibility properties of the material.

  12. Amorphous to crystal conversion as a mechanism governing the structure of luminescent YVO4:Eu nanoparticles.

    Science.gov (United States)

    Fleury, Blaise; Neouze, Marie-Alexandra; Guigner, Jean-Michel; Menguy, Nicolas; Spalla, Olivier; Gacoin, Thierry; Carriere, David

    2014-03-25

    The development of functional materials by taking advantage of the physical properties of nanoparticles needs an optimal control over their size and crystal quality. In this context, the synthesis of crystalline oxide nanoparticles in water at room temperature is a versatile and industrially appealing process but lacks control especially for "large" nanoparticles (>30 nm), which commonly consist of agglomerates of smaller crystalline primary grains. Improvement of these syntheses is hampered by the lack of knowledge on possible intermediate, noncrystalline stages, although their critical importance has already been outlined in crystallization processes. Here, we show that during the synthesis of luminescent Eu-doped YVO4 nanoparticles a transient amorphous network forms with a two-level structuration. These two prestructuration scales constrain topologically the nucleation of the nanometer-sized crystalline primary grains and their aggregation in nanoparticles, respectively. This template effect not only clarifies why the crystal size is found independent of the nucleation rate, in contradiction with the classical nucleation models, but also supports the possibility to control the final nanostructure with the amorphous phase.

  13. Hydrothermal synthesis of size-controllable Yttrium Orthovanadate (YVO{sub 4}) nanoparticles and its application in photocatalytic degradation of direct blue dye

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, R.M., E-mail: redama123@yahoo.com [Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Advanced Materials Department, Central Metallurgical R and D Institute, CMRDI, P.O. Box 87, Helwan, Cairo 11421 (Egypt); Harraz, F.A. [Advanced Materials Department, Central Metallurgical R and D Institute, CMRDI, P.O. Box 87, Helwan, Cairo 11421 (Egypt); Mkhalid, I.A. [Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2012-08-15

    Graphical abstract: XRD patterns of YVO{sub 4} nanopowders prepared at different hydrothermal times; where Y{sub 1} = 4 h, Y{sub 2} = 8 h, Y{sub 3} = 12 h and Y{sub 4} = 24 h. Highlights: Black-Right-Pointing-Pointer Size control of Yttrium Orthovanadate. Black-Right-Pointing-Pointer Hydrothermal synthesis. Black-Right-Pointing-Pointer Removal of direct blue dye. - Abstract: Sized-controlled YVO{sub 4} nanoparticles have been synthesized by a simple hydrothermal method by changing hydrothermal time from 4 to 24 h. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (Brunauer-Emmett-Teller (BET)), and ultraviolet-visible spectroscopy (UV-vis) measurements. The results showed that the size of as-synthesized YVO{sub 4} nanoparticles was in the range of 11-40 nm and was extremely dependent on the hydrothermal time. Photocatalytic measurement showed that the YVO{sub 4} nanoparticles with particle size of about 11 nm (prepared by 4 h hydrothermal time) possess superior photocatalytic properties in the decolorization of direct blue dye. Due to simple preparation, high photocatalytic oxidation of direct blue dye and low cost, the YVO{sub 4} photocatalyst is a potential candidate for pollutants removal and will find wide application in the coming future in photocatalytic oxidation processes. The overall kinetics of photodegradation of direct blue dye using YVO{sub 4} nanopowders photocatalyst was found to be of first order. The photocatalyst could be easily removed from the reaction mixture and its recyclability with no loss of activity was possible for six times. The catalytic performance was found to decrease by 5% after run number six.

  14. US Naval Observatory Hourly Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly observations journal from the National Observatory in Washington DC. The observatory is the first station in the United States to produce hourly observations...

  15. Italian Volcano Supersites

    Science.gov (United States)

    Puglisi, G.

    2011-12-01

    Volcanic eruptions are among the geohazards that may have a substantial economic and social impact, even at worldwide scale. Large populated regions are prone to volcanic hazards worldwide. Even local phenomena may affect largely populated areas and in some cases even megacities, producing severe economic losses. On a regional or global perspective, large volcanic eruptions may affect the climate for years with potentially huge economic impacts, but even relatively small eruptions may inject large amounts of volcanic ash in the atmosphere and severely affect air traffic over entire continents. One of main challenges of the volcanological community is to continuously monitor and understand the internal processes leading to an eruption, in order to give substantial contributions to the risk reduction. Italian active volcanoes constitute natural laboratories and ideal sites where to apply the cutting-edge volcano observation systems, implement new monitoring systems and to test and improve the most advanced models and methods for investigate the volcanic processes. That's because of the long tradition of volcanological studies resulting into long-term data sets, both in-situ and from satellite systems, among the most complete and accurate worldwide, and the large spectrum of the threatening volcanic phenomena producing high local/regional/continental risks. This contribution aims at presenting the compound monitoring systems operating on the Italian active volcanoes, the main improvements achieved during the recent studies direct toward volcanic hazard forecast and risk reductions and the guidelines for a wide coordinated project aimed at applying the ideas of the GEO Supersites Initiative at Mt. Etna and Campi Flegrei / Vesuvius areas.

  16. Galactic Super-volcano in Action

    Science.gov (United States)

    2010-08-01

    A galactic "super-volcano" in the massive galaxy M87 is erupting and blasting gas outwards, as witnessed by NASA's Chandra X-ray Observatory and NSF's Very Large Array. The cosmic volcano is being driven by a giant black hole in the galaxy's center and preventing hundreds of millions of new stars from forming. Astronomers studying this black hole and its effects have been struck by the remarkable similarities between it and a volcano in Iceland that made headlines earlier this year. At a distance of about 50 million light years, M87 is relatively close to Earth and lies at the center of the Virgo cluster, which contains thousands of galaxies. M87's location, coupled with long observations over Chandra's lifetime, has made it an excellent subject for investigations of how a massive black hole impacts its environment. "Our results show in great detail that supermassive black holes have a surprisingly good control over the evolution of the galaxies in which they live," said Norbert Werner of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University and the SLAC National Accelerator Laboratory, who led one of two papers describing the study. "And it doesn't stop there. The black hole's reach extends ever farther into the entire cluster, similar to how one small volcano can affect practically an entire hemisphere on Earth." The cluster surrounding M87 is filled with hot gas glowing in X-ray light, which is detected by Chandra. As this gas cools, it can fall toward the galaxy's center where it should continue to cool even faster and form new stars. However, radio observations with the Very Large Array suggest that in M87 jets of very energetic particles produced by the black hole interrupt this process. These jets lift up the relatively cool gas near the center of the galaxy and produce shock waves in the galaxy's atmosphere because of their supersonic speed. The scientists involved in this research have found the interaction of this cosmic

  17. BBO四倍频全固态Nd:YVO4紫外激光器%ALL-SOLID-STATE Nd:YVO4 UV LASER AT 266nm BY FOURTH HARMONIC USING A BBO CRYSTAL

    Institute of Scientific and Technical Information of China (English)

    何京良; 卢兴强; 贾玉磊; 满宝元; 祝世宁; 朱永元

    2000-01-01

    报道了用BBO晶体对激光二极管抽运Nd:YVO4晶体声光调Q产生的1.064μm激光进行四倍频,实现平均功率为63mW准连续波266nm紫外激光运转,重复频率为12.5kHz、单脉冲能量5μJ、峰值功率达252W,绿光-紫外光转换效率达11%.

  18. Fabrication of White LED Using InGaN Blue LED and Ce3+:YVO4 Fluorescence%用Ce3+:YVO4晶体荧光粉与蓝光LED制造自然白光LED

    Institute of Scientific and Technical Information of China (English)

    刘景旺

    2007-01-01

    本文报导了通过结合自行制备的掺铈钒酸钇晶体(Ce3+:YVO4)荧光粉与InGaN/GaN蓝光发光二极管(LED)结合而得的白光发光二极管(W-LED).在室温、正向电压3.5V、正向电流20mA时W-LED的CIE色坐标为(0.32,0.37),接近纯白色(0.33,0.33).

  19. Picosecond pulses of variable duration from a high-power passively mode-locked Nd:YVO(4) laser free of spatial hole burning.

    Science.gov (United States)

    Nadeau, Marie-Christine; Petit, Stéphane; Balcou, Philippe; Czarny, Romain; Montant, Sébastien; Simon-Boisson, Christophe

    2010-05-15

    We report on a high-power passively mode-locked TEM(00)Nd:YVO(4) oscillator, 888 nm diode-pumped, with pulse durations adjustable between 46 ps and 12 ps. The duration tunability was obtained by varying the output coupler (OC) transmission while avoiding resorting to spatial hole burning (SHB) for pulse shortening. At a repetition rate of 91 MHz and for an output power ranging from 15 Wto45 W, we produced SHB-free 12-ps-to32-ps-long pulses. Within this range of power, these are the shortest pulse durations obtained directly from Nd:YVO(4) oscillators.

  20. 1.34μm Nd:YVO4 high efficiency laser end-pumped by diode-laser of flat-concave cavity type

    Institute of Scientific and Technical Information of China (English)

    Shang Lian-Ju; Ning Ji-Ping

    2005-01-01

    The parameters of 1.34μm Nd:YVO4 laser end-pumped with flat-concave cavity are theoretically analysed. The analysis in this paper may be helpful to the designing of kindred lasers. The operation of 1.34μm Nd:YVO4 laser end-pumped by a diode-laser with flat-concave cavity is achieved. The output power of 3.51W at 1.34μm and optical to optical conversion efficiency of 39.0% are obtained at the pump power of 9.0W.

  1. Continuous-Wave Green Laser of 9.9W by Intracavity Frequency Doubling in Laser Diode Single-End-Pumped Nd:YVO4/LBO

    Institute of Scientific and Technical Information of China (English)

    BAI Yang; LI Long; CHEN Hao-Wei; YANG Zhi; BAI Jin-Tao

    2004-01-01

    @@ A maximum of 9.9 W cw TEM00 output at 532nm laser has been obtained by intracavity frequency doubling with LBO in laser-diode single-end-pumped Nd:YVO4. The Nd:YVO4/LBO green laser has a simple three mirror V-fold cavity structure. The optical-optical conversion efficiency was 34.8%. Based on the equation of thermal conduction, a general solution for the laser-crystal interior temperature distribution is obtained by the semi-analytical thermal analysis method.

  2. Cultural heritage of astronomical observatories

    Science.gov (United States)

    Wolfschmidt, Gudrun

    2011-06-01

    We present the results of the ICOMOS international symposium ``Cultural Heritage of Astronomical Observatories (around 1900) - From Classical Astronomy to Modern Astrophysics'' (Oct. 2008). The objective of the symposium was to discuss the relevance of modern observatories to the cultural heritage of humankind and to select partner observatories which, due to the date of their construction or to their architectural or scientific importance are comparable to Hamburg Observatory, as international cooperation partners for a serial trans-national application.

  3. Ruiz Volcano: Preliminary report

    Science.gov (United States)

    Ruiz Volcano, Colombia (4.88°N, 75.32°W). All times are local (= GMT -5 hours).An explosive eruption on November 13, 1985, melted ice and snow in the summit area, generating lahars that flowed tens of kilometers down flank river valleys, killing more than 20,000 people. This is history's fourth largest single-eruption death toll, behind only Tambora in 1815 (92,000), Krakatau in 1883 (36,000), and Mount Pelée in May 1902 (28,000). The following briefly summarizes the very preliminary and inevitably conflicting information that had been received by press time.

  4. Continuous monitoring of Hawaiian volcanoes using thermal cameras

    Science.gov (United States)

    Patrick, M. R.; Orr, T. R.; Antolik, L.; Lee, R.; Kamibayashi, K.

    2012-12-01

    Thermal cameras are becoming more common at volcanoes around the world, and have become a powerful tool for observing volcanic activity. Fixed, continuously recording thermal cameras have been installed by the Hawaiian Volcano Observatory in the last two years at four locations on Kilauea Volcano to better monitor its two ongoing eruptions. The summit eruption, which began in March 2008, hosts an active lava lake deep within a fume-filled vent crater. A thermal camera perched on the rim of Halema`uma`u Crater, acquiring an image every five seconds, has now captured about two years of sustained lava lake activity, including frequent lava level fluctuations, small explosions , and several draining events. This thermal camera has been able to "see" through the thick fume in the crater, providing truly 24/7 monitoring that would not be possible with normal webcams. The east rift zone eruption, which began in 1983, has chiefly consisted of effusion through lava tubes onto the surface, but over the past two years has been interrupted by an intrusion, lava fountaining, crater collapse, and perched lava lake growth and draining. The three thermal cameras on the east rift zone, all on Pu`u `O`o cone and acquiring an image every several minutes, have captured many of these changes and are providing an improved means for alerting observatory staff of new activity. Plans are underway to install a thermal camera at the summit of Mauna Loa to monitor and alert to any future changes there. Thermal cameras are more difficult to install, and image acquisition and processing are more complicated than with visual webcams. Our system is based in part on the successful thermal camera installations by Italian volcanologists on Stromboli and Vulcano. Equipment includes custom enclosures with IR transmissive windows, power, and telemetry. Data acquisition is based on ActiveX controls, and data management is done using automated Matlab scripts. Higher-level data processing, also done with

  5. ESO's Two Observatories Merge

    Science.gov (United States)

    2005-02-01

    On February 1, 2005, the European Southern Observatory (ESO) has merged its two observatories, La Silla and Paranal, into one. This move will help Europe's prime organisation for astronomy to better manage its many and diverse projects by deploying available resources more efficiently where and when they are needed. The merged observatory will be known as the La Silla Paranal Observatory. Catherine Cesarsky, ESO's Director General, comments the new development: "The merging, which was planned during the past year with the deep involvement of all the staff, has created unified maintenance and engineering (including software, mechanics, electronics and optics) departments across the two sites, further increasing the already very high efficiency of our telescopes. It is my great pleasure to commend the excellent work of Jorge Melnick, former director of the La Silla Observatory, and of Roberto Gilmozzi, the director of Paranal." ESO's headquarters are located in Garching, in the vicinity of Munich (Bavaria, Germany), and this intergovernmental organisation has established itself as a world-leader in astronomy. Created in 1962, ESO is now supported by eleven member states (Belgium, Denmark, Finland, France, Germany, Italy, The Netherlands, Portugal, Sweden, Switzerland, and the United Kingdom). It operates major telescopes on two remote sites, all located in Chile: La Silla, about 600 km north of Santiago and at an altitude of 2400m; Paranal, a 2600m high mountain in the Atacama Desert 120 km south of the coastal city of Antofagasta. Most recently, ESO has started the construction of an observatory at Chajnantor, a 5000m high site, also in the Atacama Desert. La Silla, north of the town of La Serena, has been the bastion of the organization's facilities since 1964. It is the site of two of the most productive 4-m class telescopes in the world, the New Technology Telescope (NTT) - the first major telescope equipped with active optics - and the 3.6-m, which hosts HARPS

  6. Q-switched mode-locked diode-pumped Nd:YVO4 laser with a saturable Bragg reflector

    Institute of Scientific and Technical Information of China (English)

    Juan Du(杜鹃); Jingliang He(何京良); Jie Liu(刘杰); Qiuxia Jiang(姜秋霞); Sheng Liu(刘胜); Huitian Wang(王慧田)

    2004-01-01

    We demonstrated a diode-pumped passively Q-switched mode-locked Nd:YVO4 laser by using a relaxed saturable Bragg reflector (SBR). Stable mode-locked pulse train with the repetition rate of ~230 MHz was achieved and the pulse train was modulated by the Q-switched envelope with the repetition rate of ~150 kHz. The maximum output of 4 W was obtained under the pump power of 13.5 W. The optical-to-optical efficiency was 30%. We also discussed the transition of each process having emerged.

  7. Q-switched mode-locked diode-pumped Nd:YVO4 laser with a saturable Bragg reflector

    Institute of Scientific and Technical Information of China (English)

    杜鹃; 何京良; 刘杰; 姜秋霞; 刘胜; 王慧田

    2004-01-01

    We demonstrated a diode-pumped passively Q-switched mode-locked Nd:YVO4 laser by using a relaxed saturable Bragg reflector (SBR). Stable mode-locked pulse train with the repetition rate of ~230 MHz was achieved and the pulse train was modulated by the Q-switched envelope with the repetition rate of ~150kHz. The maximum output of 4 W was obtained under the pump power of 13.5 W. The optical-to-optical efficiency was 30%. We also discussed the transition of each process having emerged.

  8. Multi-watt Q-switched Nd:YVO4 laser with GaAs output coupler

    Institute of Scientific and Technical Information of China (English)

    Ping Li(李平); Qingpu Wang(王青圃); Shichen Li(李世忱); Jie Lian(连结); Baomin Ma(马宝民); Jingliang He(何京良)

    2003-01-01

    A passively Q-switched operation of a diode-pumped Nd:YVO4 laser is demonstrated, in which a GaAs film is used as the saturable absorber as well as the output coupler. At the pump power of 10 W, a stable fundamental-mode average power output of 2.11 W was obtained with a pulse duration of 140 ns, pulse energy of 76 μJ and pulse repetition rate of 28 kHz. A theoretical analysis that describes the passive Q-switching dynamics of GaAs is presented.

  9. Compact and high repetition rate Kerr-lens mode-locked 532 nm Nd:YVO4 laser

    Science.gov (United States)

    Li, Zuohan; Peng, Jiying; Yuan, Ruixia; Wang, Tongtong; Yao, Jianquan; Zheng, Yi

    2015-11-01

    A compact and feasible CW Kerr-lens-induced mode-locked 532 nm Nd:YVO4 laser system was experimentally demonstrated for the first time with theoretical analysis. Kerr-lens mode locking with intracavity second harmonic generation provides a promising method to generate a high-repetition-rate picosecond green laser. With an incident pump power of 6 W, the average output power of mode locking was 258 mW at a high repetition rate of 1.1 GHz.

  10. LD-pumped Nd:YVO sub 4 frequency-doubled by CPM LBO laser at 671 nm

    CERN Document Server

    Zheng Quan; Qian Long Sheng; Zhao Ling

    2001-01-01

    A design of LD-pumped high efficient Nd:YVO sub 4 /LBO red laser is reported. Using critical phase-matching LBO for the first time, 671 nm red laser is obtained by 1.342 mu m intracavity frequency doubling. With 800 mW incident pump laser, 52 mW and 97 mW TEM00 mode red laser output are obtained by II-typed and I-typed LBO. The optical-to-optical conversions are up to 6.5% and 12.1% respectively

  11. Expanding the HAWC Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Johanna [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-17

    The High Altitude Water Cherenkov Gamma-Ray Observatory is expanding its current array of 300 water tanks to include 350 outrigger tanks to increase sensitivity to gamma rays above 10 TeV. This involves creating and testing hardware with which to build the new tanks, including photomultiplier tubes, high voltage supply units, and flash analog to digital converters. My responsibilities this summer included preparing, testing and calibrating that equipment.

  12. Hazard information management, interagency coordination, and impacts of the 2005-2006 eruption of Augustine Volcano: Chapter 28 in The 2006 eruption of Augustine Volcano, Alaska

    Science.gov (United States)

    Neal, Christina A.; Murray, Thomas L.; Power, John A.; Adleman, Jennifer N.; Whitmore, Paul M.; Osiensky, Jeffery M.; Power, John A.; Coombs, Michelle L.; Freymueller, Jeffrey T.

    2010-01-01

    Dissemination of volcano-hazard information in coordination with other Federal, State, and local agencies is a primary responsibility of the Alaska Volcano Observatory (AVO). During the 2005-6 eruption of Augustine Volcano in Alaska, AVO used existing interagency relationships and written protocols to provide hazard guidance before, during, and after eruptive events. The 2005-6 eruption was notable because of the potential for volcanogenic tsunami, which required establishment of a new procedure for alerts of possible landslide-induced tsunami in Cook Inlet. Despite repeated ash-cloud generating explosions and far-traveled ash clouds, impacts from the event were relatively minor. Primary economic losses occurred when air carriers chose to avoid flights into potentially unsafe conditions. Post-eruption evaluations by agencies involved in the response indicated weaknesses in information centralization and availability of specific information regarding ash fall hazards in real time.

  13. Preliminary volcano-hazard assessment for Iliamna Volcano, Alaska

    Science.gov (United States)

    Waythomas, Christopher F.; Miller, Thomas P.

    1999-01-01

    Iliamna Volcano is a 3,053-meter-high, ice- and snow-covered stratovolcano in the southwestern Cook Inlet region about 225 kilometers southwest of Anchorage and about 100 kilometers northwest of Homer. Historical eruptions of Iliamna Volcano have not been positively documented; however, the volcano regularly emits steam and gas, and small, shallow earthquakes are often detected beneath the summit area. The most recent eruptions of the volcano occurred about 300 years ago, and possibly as recently as 90-140 years ago. Prehistoric eruptions have generated plumes of volcanic ash, pyroclastic flows, and lahars that extended to the volcano flanks and beyond. Rock avalanches from the summit area have occurred numerous times in the past. These avalanches flowed several kilometers down the flanks and at least two large avalanches transformed to cohesive lahars. The number and distribution of known volcanic ash deposits from Iliamna Volcano indicate that volcanic ash clouds from prehistoric eruptions were significantly less voluminous and probably less common relative to ash clouds generated by eruptions of other Cook Inlet volcanoes. Plumes of volcanic ash from Iliamna Volcano would be a major hazard to jet aircraft using Anchorage International Airport and other local airports, and depending on wind direction, could drift at least as far as the Kenai Peninsula and beyond. Ashfall from future eruptions could disrupt oil and gas operations and shipping activities in Cook Inlet. Because Iliamna Volcano has not erupted for several hundred years, a future eruption could involve significant amounts of ice and snow that could lead to the formation of large lahars and downstream flooding. The greatest hazards in order of importance are described below and shown on plate 1.

  14. Megalithic observatory Kokino

    Science.gov (United States)

    Cenev, Gj.

    2006-05-01

    In 2001, on the footpath of a mountain peak, near the village of Kokino, archeologist Jovica Stankovski discovered an archeological site from The Bronze Age. The site occupies a large area and is scaled in two levels. Several stone seats (thrones) are dominant in this site and they are pointing towards the east horizon. The high concentration of the movable archeological material found on the upper platform probably indicates its use in a function containing still unknown cult activities. Due to precise measurements and a detailed archaeoastronomical analysis of the site performed in the past three years by Gjore Cenev, physicist from the Planetarium in Skopje, it was shown that the site has characteristics of a sacred site, but also of a Megalithic Observatory. The markers found in this observatory point on the summer and winter solstices and spring and autumn equinoxes. It can be seen that on both sides of the solstice markers, that there are markers for establishing Moon's positions. The markers are crafted in such a way that for example on days when special rites were performed (harvest rites for example) the Sun filled a narrow space of the marker and special ray lighted the man sitting on only one of the thrones, which of course had a special meaning. According to the positions of the markers that are used for Sun marking, especially on the solstice days, it was calculated that this observatory dates from 1800 B.C.

  15. Using Bayesian Belief Networks To Assess Volcano State from Multiple Monitoring Timeseries And Other Evidence

    Science.gov (United States)

    Odbert, Henry; Aspinall, Willy

    2013-04-01

    When volcanoes exhibit unrest or become eruptively active, science-based decision support invariably is sought by civil authorities. Evidence available to scientists about a volcano's internal state is usually indirect, secondary or very nebulous.Advancement of volcano monitoring technology in recent decades has increased the variety and resolution of multi-parameter timeseries data recorded at volcanoes. Monitoring timeseries may be interpreted in real time by observatory staff and are often later subjected to further analytic scrutiny by the research community at large. With increasing variety and resolution of data, interpreting these multiple strands of parallel, partial evidence has become increasingly complex. In practice, interpretation of many timeseries involves familiarity with the idiosyncracies of the volcano, the monitoring techniques, the configuration of the recording instrumentation, observations from other datasets, and so on. Assimilation of this knowledge is necessary in order to select and apply the appropriate statistical techniques required to extract the required information. Bayesian Belief Networks (BBNs) use probability theory to treat and evaluate uncertainties in a rational and auditable scientific manner, but only to the extent warranted by the strength of the available evidence. The concept is a suitable framework for marshalling multiple observations, model results and interpretations - and associated uncertainties - in a methodical manner. The formulation is usually implemented in graphical form and could be developed as a tool for near real-time, ongoing use in a volcano observatory, for example. We explore the application of BBNs in analysing volcanic timeseries, the certainty with which inferences may be drawn, and how they can be updated dynamically. Such approaches provide a route to developing analytical interface(s) between volcano monitoring analyses and probabilistic hazard analysis. We discuss the use of BBNs in hazard

  16. Mount Rainier active cascade volcano

    Science.gov (United States)

    1994-01-01

    Mount Rainier is one of about two dozen active or recently active volcanoes in the Cascade Range, an arc of volcanoes in the northwestern United States and Canada. The volcano is located about 35 kilometers southeast of the Seattle-Tacoma metropolitan area, which has a population of more than 2.5 million. This metropolitan area is the high technology industrial center of the Pacific Northwest and one of the commercial aircraft manufacturing centers of the United States. The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home to approximately a million people in southwestern Washington and northwestern Oregon. Mount Rainier is an active volcano. It last erupted approximately 150 years ago, and numerous large floods and debris flows have been generated on its slopes during this century. More than 100,000 people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10,000 years. A major volcanic eruption or debris flow could kill thousands of residents and cripple the economy of the Pacific Northwest. Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood.

  17. Mount Rainier active cascade volcano

    Science.gov (United States)

    Mount Rainier is one of about two dozen active or recently active volcanoes in the Cascade Range, an arc of volcanoes in the northwestern United States and Canada. The volcano is located about 35 kilometers southeast of the Seattle-Tacoma metropolitan area, which has a population of more than 2.5 million. This metropolitan area is the high technology industrial center of the Pacific Northwest and one of the commercial aircraft manufacturing centers of the United States. The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home to approximately a million people in southwestern Washington and northwestern Oregon. Mount Rainier is an active volcano. It last erupted approximately 150 years ago, and numerous large floods and debris flows have been generated on its slopes during this century. More than 100,000 people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10,000 years. A major volcanic eruption or debris flow could kill thousands of residents and cripple the economy of the Pacific Northwest. Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood.

  18. Research and Development of 200 W High Beam Quality All-Solid-State Nd:YVO4 Slab Laser%200 W高光束质量全固态Nd:YVO4板条激光器研究

    Institute of Scientific and Technical Information of China (English)

    毛叶飞; 张恒利; 徐浏; 何京良; 孙肖; 邢冀川; 辛建国

    2012-01-01

    To achieve the laser beam with high quality and medium power, a laser diode stack dual-end-pumped Nd: YVO4 slab laser with folded hybrid cavity has been developed. Its maximum output power is 202 W and optical conversion efficiency is 47. 5%. The M2 factor in horizontal and vertical direction is 1. 7 and 2. 3, respectively.%为了获得高光束质量的中功率激光,利用激光二极管阵列双端抽运Nd:YVO4,采用折叠混合腔结构的板条结构,获得激光的最大输出功率为202 W,光-光转换效率为47.5%;光束质量M2因子在水平方向和垂直方向分别为1.72和2.25.

  19. Side-pumped Nd:YVO{sub 4} cw laser with grazing-incidence small angle configuration; Laser de Nd:YVO{sub 4} bombeado transversalmente em configuracao com angulo rasante interno

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, Fabiola de Almeida

    2006-07-01

    Within the existing variety of laser cavity geometries and gain materials there is one combination that is particularly interesting because of its reduced complexity and high efficiency: the edge-pumped slab-laser using grazing-incidence geometry and a gain media with a very high pump absorption cross-section. In this work we studied a diode side-pumped Nd:YVO{sub 4} cw laser. We describe a single and a multiple bounce laser configurations. We demonstrate 22 W of multimode output power for 35 watts of pump power with a single pass through the gain media. A high optical-to-optical conversion efficiency of 63% and a slope efficiency of 74% with a very compact and simple Nd:YVO{sub 4} cavity that uses joint stability zones was achieved. The beam quality was M{sup 2} = 26 x 11 in the horizontal and vertical direction, respectively. With a double pass configuration we achieved 17 watts with a better beam quality of M{sup 2} = 3,4 x 3,7, in the horizontal and vertical direction, respectively. (author)

  20. Soufriere Hills Volcano

    Science.gov (United States)

    2002-01-01

    In this ASTER image of Soufriere Hills Volcano on Montserrat in the Caribbean, continued eruptive activity is evident by the extensive smoke and ash plume streaming towards the west-southwest. Significant eruptive activity began in 1995, forcing the authorities to evacuate more than 7,000 of the island's original population of 11,000. The primary risk now is to the northern part of the island and to the airport. Small rockfalls and pyroclastic flows (ash, rock and hot gases) are common at this time due to continued growth of the dome at the volcano's summit.This image was acquired on October 29, 2002 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is part of NASA

  1. Catalog of earthquake hypocenters at Alaskan volcanoes: January 1 through December 31, 2009

    Science.gov (United States)

    Dixon, James P.; Stihler, Scott D.; Power, John A.; Searcy, Cheryl K.

    2010-01-01

    Between January 1 and December 31, 2009, the Alaska Volcano Observatory (AVO) located 8,829 earthquakes, of which 7,438 occurred within 20 kilometers of the 33 volcanoes with seismograph subnetworks. Monitoring highlights in 2009 include the eruption of Redoubt Volcano, as well as unrest at Okmok Caldera, Shishaldin Volcano, and Mount Veniaminof. Additionally severe seismograph subnetwork outages resulted in four volcanoes (Aniakchak, Fourpeaked, Korovin, and Veniaminof) being removed from the formal list of monitored volcanoes in late 2009. This catalog includes descriptions of: (1) locations of seismic instrumentation deployed during 2009; (2) earthquake detection, recording, analysis, and data archival systems; (3) seismic velocity models used for earthquake locations; (4) a summary of earthquakes located in 2009; and (5) an accompanying UNIX tar-file with a summary of earthquake origin times, hypocenters, magnitudes, phase arrival times, location quality statistics, daily station usage statistics, all files used to determine the earthquake locations in 2009, and a dataless SEED volume for the AVO seismograph network.

  2. Digital Data for Volcano Hazards of the Mount Hood Region, Oregon

    Science.gov (United States)

    Schilling, S.P.; Doelger, S.; Scott, W.E.; Pierson, T.C.; Costa, J.E.; Gardner, C.A.; Vallance, J.W.; Major, J.J.

    2008-01-01

    Snow-clad Mount Hood dominates the Cascade skyline from the Portland metropolitan area to the wheat fields of Wasco and Sherman Counties. The mountain contributes valuable water, scenic, and recreational resources that help sustain the agricultural and tourist segments of the economies of surrounding cities and counties. Mount Hood is also one of the major volcanoes of the Cascade Range, having erupted repeatedly for hundreds of thousands of years, most recently during two episodes in the past 1,500 yr. The last episode ended shortly before the arrival of Lewis and Clark in 1805. When Mount Hood erupts again, it will severely affect areas on its flanks and far downstream in the major river valleys that head on the volcano. Volcanic ash may fall on areas up to several hundred kilometers downwind. The purpose of the volcano hazard report USGS Open-File Report 97-89 (Scott and others, 1997) is to describe the kinds of hazardous geologic events that have happened at Mount Hood in the past and to show which areas will be at risk when such events occur in the future. This data release contains the geographic information system (GIS) data layers used to produce the Mount Hood volcano hazard map in USGS Open-File Report 97-89. Both proximal and distal hazard zones were delineated by scientists at the Cascades Volcano Observatory and depict various volcano hazard areas around the mountain. A second data layer contains points that indicate estimated travel times of lahars.

  3. Seismic signature of a phreatic explosion: Hydrofracturing damage at Karthala volcano, Grande Comore Island, Indian Ocean

    Science.gov (United States)

    Savin, C.; Grasso, J.-R.; Bachelery, P.

    2005-01-01

    Karthala volcano is a basaltic shield volcano with an active hydrothermal system that forms the southern two-thirds of the Grande Comore Island, off the east coat of Africa, northwest of Madagascar. Since the start of volcano monitoring by the local volcano observatory in 1988, the July 11th, 1991 phreatic eruption was the first volcanic event seismically recorded on this volcano, and a rare example of a monitored basaltic shield. From 1991 to 1995 the VT locations, 0.5activation of the whole hydrothermal system, as roughly sized by the distribution of VT hypocenters. The seismicity rate in 1995 was still higher than the pre-eruption seismicity rate, and disagrees with the time pattern of thermo-elastic stress readjustment induced by single magma intrusions at basaltic volcanoes. We propose that it corresponds to the still ongoing relaxation of pressure heterogeneity within the hydrothermal system as suggested by the few LP events that still occurred in 1995. ?? Springer-Verlag 2005.

  4. Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Founded in 1912 at the edge of the caldera of Kīlauea Volcano, HVO was the vision of Thomas A. Jaggar, Jr., a geologist from the Massachusetts Institute of Technology, whose studies of natural disasters around the world had convinced him that systematic, continuous observations of seismic and volcanic activity were needed to better understand—and potentially predict—earthquakes and volcanic eruptions. Jaggar summarized the aim of HVO by stating that “the work should be humanitarian” and have the goals of developing “prediction and methods of protecting life and property on the basis of sound scientific achievement.” These goals align well with those of the USGS, whose mission is to serve the Nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage natural resources; and enhance and protect our quality of life.

  5. Direct comparison of the thermal lenses of diode-end-pumped Nd:YVO4 and Nd:GdVO4 lasers using a simple evaluation technique

    CSIR Research Space (South Africa)

    Esser, MJD

    2006-01-01

    Full Text Available In this work, the thermal lenses generated in diode-end-pumped Nd:YVO4 and Nd:GdVO4 lasers were evaluated and compared using a simple technique based on the stability criteria of a plane-parallel laser resonator [example 1], as shown in the top...

  6. Effect of Yb doping on the refractive index and thermo-optic coefficient of YVO4 single crystals.

    Science.gov (United States)

    Soharab, M; Bhaumik, Indranil; Bhatt, R; Saxena, A; Karnal, A K; Gupta, P K

    2017-02-20

    Single crystals of YVO4 with different doping concentrations of Yb (1.5, 3.0, 8.0, and 15.0 at. %) and with good crystalline quality (FWHM ∼43-55 arc sec of rocking curve) were grown by the optical floating zone technique. Refractive index measurements were carried out at four wavelengths as a function of temperature. The measurements show that as the doping concentration of Yb is increased, the refractive index varies marginally for ne whereas there is a significant change in the value of no. The thermo-optic coefficient (dn/dT) was found to be positive with a value ∼10-5/°C, which is 1 order higher than that for the undoped YVO4 crystal. The thermo-optic coefficient is higher for ne compared to that of no. Also, a set of relations describing the wavelength dependence of the thermo-optic coefficient were established that are useful for calculating the thermo-optic coefficient at any temperature in the range 30°C-150°C and at any wavelength in the range 532-1551 nm.

  7. Micromachining of carbon nanocomposites with Nd:YAG and Nd:YVO4 frequency-converted solid state lasers

    Science.gov (United States)

    Dosser, Larry; Hix, Ken; Hartke, Kevin; Vaia, Richard; Li, Mingwei

    2004-07-01

    Carbon nanocomposites consist of thermoset and thermoplastic materials filled with carbon nano-particles (nanotubes, bucky balls, etc.). This new and innovative group of materials offers many advantages over standard polymers such as electrical/thermal conductivity and improved structural properties. In the current study, Nd:YAG and Nd:YVO4 solid-state lasers were used to micromachine carbon nanocomposite thermoplastic materials. Experimentation was completed to compare the ability to laser micromachine carbon nanomaterial, carbon black, and unfilled polyurethane. The experimentation studied the relationship between repetition rate, travel speed, and material removal rate. The processing consisted of cutting channels into the materials using an Nd:YVO4 laser at 1064, 532, and 355 nm wavelengths. The material removal rate and groove width were quantified for all wavelengths and compared versus the experimental variables. Trials were also completed on laser machining deep channels using an Nd:YAG laser and polyetheretherketone (PEEK) filled with carbon black and carbon nanofiber. The results of the experimentation show similar material removal rates for carbon black and carbon nanofiber filled polyurethane. The PEEK material exhibited high aspect ratio channels with both carbon black and carbon nanofiber fillers. Laser micromachining of polymers whcih were previously unmachinable using infra-red has been demonstrated.

  8. Dynamical properties of total intensity fluctuation spectrum in two-mode Nd:YVO4 microchip laser

    Science.gov (United States)

    Zhang, Shao-Hui; Shu-Lian, Zhang; Tan, Yi-Dong; Sun, Li-Qun

    2015-12-01

    We investigate the total intensity fluctuation spectrum of the two-longitudinal- mode Nd:YVO4 microchip laser (ML). We find that low-frequency relaxation oscillation (RO) peaks still appear in the total intensity fluctuation spectrum, which is different from a previous research result that the low-frequency RO peaks exist in the spectrum of the individual mode but compensate for each other totally in the total intensity fluctuation spectrum. Taking the spatial hole-burning effect into account, one and two-mode rate equations for Nd:YVO4 ML laser are established and studied. Based on the theoretical model, we find that when the gains and losses for two longitudinal models are different, a low-frequency RO peak will appear in the total intensity fluctuation spectrum, while when they share the same gain and loss, the total spectrum will behave like that of a single mode laser. Theoretical simulation results coincide with experimental results very well. Project supported by the Beijing Higher Education Young Elite Teacher Project, China (Grant No. YETP0086), the Tsinghua University Initiative Scientific Research Programme, China (Grant No. 2012Z02166), and the Special-funded Programme on National Key Scientific Instruments and Equipment Development of China (Grant No. 2011YQ04013603).

  9. Astronomical publications of Melbourne Observatory

    Science.gov (United States)

    Andropoulos, Jenny Ioanna

    2014-05-01

    During the second half of the 19th century and the first half of the 20th century, four well-equipped government observatories were maintained in Australia - in Melbourne, Sydney, Adelaide and Perth. These institutions conducted astronomical observations, often in the course of providing a local time service, and they also collected and collated meteorological data. As well, some of these observatories were involved at times in geodetic surveying, geomagnetic recording, gravity measurements, seismology, tide recording and physical standards, so the term "observatory" was being used in a rather broad sense! Despite the international renown that once applied to Williamstown and Melbourne Observatories, relatively little has been written by modern-day scholars about astronomical activities at these observatories. This research is intended to rectify this situation to some extent by gathering, cataloguing and analysing the published astronomical output of the two Observatories to see what contributions they made to science and society. It also compares their contributions with those of Sydney, Adelaide and Perth Observatories. Overall, Williamstown and Melbourne Observatories produced a prodigious amount of material on astronomy in scientific and technical journals, in reports and in newspapers. The other observatories more or less did likewise, so no observatory of those studied markedly outperformed the others in the long term, especially when account is taken of their relative resourcing in staff and equipment.

  10. The Observatory Health Report

    Directory of Open Access Journals (Sweden)

    Laura Murianni

    2008-06-01

    Full Text Available

    Background: The number of indicators aiming to provide a clear picture of healthcare needs and the quality and efficiency of healthcare systems and services has proliferated in recent years. The activity of the National Observatory on Health Status in the Italian Regions is multidisciplinary, involving around 280 public health care experts, clinicians, demographers, epidemiologists, mathematicians, statisticians and economists who with their different competencies, and scientific interests aim to improve the collective health of individuals and their conditions through the use of “core indicators”. The main outcome of the National Observatory on Health Status in the Italian Regions is the “Osservasalute Report – a report on health status and the quality of healthcare assistance in the Italian Regions”.

    Methods: The Report adopts a comparative analysis, methodology and internationally validated indicators.

    Results: The results of Observatory Report show it is necessary:

    • to improve the monitoring of primary health care services (where the chronic disease could be cared through implementation of clinical path;

     • to improve in certain areas of hospital care such as caesarean deliveries, as well as the average length of stay in the pre-intervention phase, etc.;

    • to try to be more focused on the patients/citizens in our health care services; • to practice more geographical interventions to reduce the North-South divide as well as reduce gender inequity.

    Conclusions: The health status of Italian people is good with positive results and outcomes, but in the meantime some further efforts should be done especially in the South that still has to improve the quality and the organization of health care services. There are huge differences in accuracy and therefore usefulness of the reported data, both between diseases and between

  11. Portable coastal observatories

    Science.gov (United States)

    Frye, Daniel; Butman, Bradford; Johnson, Mark; von der Heydt, Keith; Lerner, Steven

    2000-01-01

    Ocean observational science is in the midst of a paradigm shift from an expeditionary science centered on short research cruises and deployments of internally recording instruments to a sustained observational science where the ocean is monitored on a regular basis, much the way the atmosphere is monitored. While satellite remote sensing is one key way of meeting the challenge of real-time monitoring of large ocean regions, new technologies are required for in situ observations to measure conditions below the ocean surface and to measure ocean characteristics not observable from space. One method of making sustained observations in the coastal ocean is to install a fiber optic cable from shore to the area of interest. This approach has the advantage of providing power to offshore instruments and essentially unlimited bandwidth for data. The LEO-15 observatory offshore of New Jersey (yon Alt et al., 1997) and the planned Katama observatory offshore of Martha's Vineyard (Edson et al., 2000) use this approach. These sites, along with other cabled sites, will play an important role in coastal ocean science in the next decade. Cabled observatories, however, have two drawbacks that limit the number of sites that are likely to be installed. First, the cable and the cable installation are expensive and the shore station needed at the cable terminus is often in an environmentally sensitive area where competing interests must be resolved. Second, cabled sites are inherently limited geographically to sites within reach of the cable, so it is difficult to cover large areas of the coastal ocean.

  12. GlobVolcano pre-operational services for global monitoring active volcanoes

    Science.gov (United States)

    Tampellini, Lucia; Ratti, Raffaella; Borgström, Sven; Seifert, Frank Martin; Peltier, Aline; Kaminski, Edouard; Bianchi, Marco; Branson, Wendy; Ferrucci, Fabrizio; Hirn, Barbara; van der Voet, Paul; van Geffen, J.

    2010-05-01

    The GlobVolcano project (2007-2010) is part of the Data User Element programme of the European Space Agency (ESA). The project aims at demonstrating Earth Observation (EO) based integrated services to support the Volcano Observatories and other mandate users (e.g. Civil Protection) in their monitoring activities. The information services are assessed in close cooperation with the user organizations for different types of volcano, from various geographical areas in various climatic zones. In a first phase, a complete information system has been designed, implemented and validated, involving a limited number of test areas and respective user organizations. In the currently on-going second phase, GlobVolcano is delivering pre-operational services over 15 volcanic sites located in three continents and as many user organizations are involved and cooperating with the project team. The set of GlobVolcano offered EO based information products is composed as follows: Deformation Mapping DInSAR (Differential Synthetic Aperture Radar Interferometry) has been used to study a wide range of surface displacements related to different phenomena (e.g. seismic faults, volcanoes, landslides) at a spatial resolution of less than 100 m and cm-level precision. Permanent Scatterers SAR Interferometry method (PSInSARTM) has been introduced by Politecnico of Milano as an advanced InSAR technique capable of measuring millimetre scale displacements of individual radar targets on the ground by using multi-temporal data-sets, estimating and removing the atmospheric components. Other techniques (e.g. CTM) have followed similar strategies and have shown promising results in different scenarios. Different processing approaches have been adopted, according to data availability, characteristic of the area and dynamic characteristics of the volcano. Conventional DInSAR: Colima (Mexico), Nyiragongo (Congo), Pico (Azores), Areanal (Costa Rica) PSInSARTM: Piton de la Fournaise (La Reunion Island

  13. The HAWC observatory

    Energy Technology Data Exchange (ETDEWEB)

    DeYoung, Tyce, E-mail: deyoung@phys.psu.edu [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States)

    2012-11-11

    The High Altitude Water Cherenkov (HAWC) observatory is a new very high energy water Cherenkov gamma ray telescope, now under construction at 4100 m altitude at Sierra Negra, Mexico. Due to its increased altitude, larger surface area and improved design, HAWC will be about 15 times more sensitive than its predecessor, Milagro. With its wide field of view and high duty factor, HAWC will be an excellent instrument for the studies of diffuse gamma ray emission, the high energy spectra of Galactic gamma ray sources, and transient emission from extragalactic objects such as GRBs and AGN, as well as surveying a large fraction of the VHE sky.

  14. The HAWC observatory

    Science.gov (United States)

    DeYoung, Tyce; HAWC Collaboration

    2012-11-01

    The High Altitude Water Cherenkov (HAWC) observatory is a new very high energy water Cherenkov gamma ray telescope, now under construction at 4100 m altitude at Sierra Negra, Mexico. Due to its increased altitude, larger surface area and improved design, HAWC will be about 15 times more sensitive than its predecessor, Milagro. With its wide field of view and high duty factor, HAWC will be an excellent instrument for the studies of diffuse gamma ray emission, the high energy spectra of Galactic gamma ray sources, and transient emission from extragalactic objects such as GRBs and AGN, as well as surveying a large fraction of the VHE sky.

  15. Next Generation Virtual Observatories

    Science.gov (United States)

    Fox, P.; McGuinness, D. L.

    2008-12-01

    Virtual Observatories (VO) are now being established in a variety of geoscience disciplines beyond their origins in Astronomy and Solar Physics. Implementations range from hydrology and environmental sciences to solid earth sciences. Among the goals of VOs are to provide search/ query, access and use of distributed, heterogeneous data resources. With many of these goals being met and usage increasing, new demands and requirements are arising. In particular there are two of immediate and pressing interest. The first is use of VOs by non-specialists, especially for information products that go beyond the usual data, or data products that are sought for scientific research. The second area is citation and attribution of artifacts that are being generated by VOs. In some sense VOs are re-publishing (re-packaging, or generating new synthetic) data and information products. At present only a few VOs address this need and it is clear that a comprehensive solution that includes publishers is required. Our work in VOs and related semantic data framework and integration areas has lead to a view of the next generation of virtual observatories which the two above-mentioned needs as well as others that are emerging. Both of the needs highlight a semantic gap, i.e. that the meaning and use for a user or users beyond the original design intention is very often difficult or impossible to bridge. For example, VOs created for experts with complex, arcane or jargon vocabularies are not accessible to the non-specialist and further, information products the non-specialist may use are not created or considered for creation. In the second case, use of a (possibly virtual) data or information product (e.g. an image or map) as an intellectual artifact that can be accessed as part of the scientific publication and review procedure also introduces terminology gaps, as well as services that VOs may need to provide. Our supposition is that formalized methods in semantics and semantic web

  16. DSN Transient Observatory

    Science.gov (United States)

    Kuiper, T. B. H.; Monroe, R. M.; White, L. A.; Garcia Miro, C.; Levin, S. M.; Majid, W. A.; Soriano, M.

    2016-11-01

    The Deep Space Network (DSN) Transient Observatory (DTO) is a signal processing facility that can monitor up to four DSN downlink bands for astronomically interesting signals. The monitoring is done commensally with reception of deep space mission telemetry. The initial signal processing is done with two CASPERa ROACH1 boards, each handling one or two baseband signals. Each ROACH1 has a 10 GBe interface with a GPU-equipped Debian Linux workstation for additional processing. The initial science programs include monitoring Mars for electrostatic discharges, radio spectral lines, searches for fast radio bursts and pulsars and SETI. The facility will be available to the scientific community through a peer review process.

  17. Volcanoes in Eruption - Set 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The word volcano is used to refer to the opening from which molten rock and gas issue from Earth's interior onto the surface, and also to the cone, hill, or mountain...

  18. Volcanoes in Eruption - Set 2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The word volcano is used to refer to the opening from which molten rock and gas issue from Earth's interior onto the surface, and also to the cone, hill, or mountain...

  19. USGS Volcano Notification Service (VNS)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Website provides a subscription service to receive an email when changes occur in the activity levels for monitored U.S. volcanoes and/or when information releases...

  20. Muon imaging of volcanoes with Cherenkov telescopes

    Science.gov (United States)

    Carbone, Daniele; Catalano, Osvaldo; Cusumano, Giancarlo; Del Santo, Melania; La Parola, Valentina; La Rosa, Giovanni; Maccarone, Maria Concetta; Mineo, Teresa; Pareschi, Giovanni; Sottile, Giuseppe; Zuccarello, Luciano

    2017-04-01

    The quantitative understanding of the inner structure of a volcano is a key feature to model the processes leading to paroxysmal activity and, hence, to mitigate volcanic hazards. To pursue this aim, different geophysical techniques are utilized, that are sensitive to different properties of the rocks (elastic, electrical, density). In most cases, these techniques do not allow to achieve the spatial resolution needed to characterize the shallowest part of the plumbing system and may require dense measurements in active zones, implying a high level of risk. Volcano imaging through cosmic-ray muons is a promising technique that allows to overcome the above shortcomings. Muons constantly bombard the Earth's surface and can travel through large thicknesses of rock, with an energy loss depending on the amount of crossed matter. By measuring the absorption of muons through a solid body, one can deduce the density distribution inside the target. To date, muon imaging of volcanic structures has been mainly achieved with scintillation detectors. They are sensitive to noise sourced from (i) the accidental coincidence of vertical EM shower particles, (ii) the fake tracks initiated from horizontal high-energy electrons and low-energy muons (not crossing the target) and (iii) the flux of upward going muons. A possible alternative to scintillation detectors is given by Cherenkov telescopes. They exploit the Cherenkov light emitted when charged particles (like muons) travel through a dielectric medium, with velocity higher than the speed of light. Cherenkov detectors are not significantly affected by the above noise sources. Furthermore, contrarily to scintillator-based detectors, Cherenkov telescopes permit a measurement of the energy spectrum of the incident muon flux at the installation site, an issue that is indeed relevant for deducing the density distribution inside the target. In 2014, a prototype Cherenkov telescope was installed at the Astrophysical Observatory of Serra

  1. GLACIERS OF THE KORYAK VOLCANO

    Directory of Open Access Journals (Sweden)

    T. M. Manevich

    2012-01-01

    Full Text Available The paper presents main glaciological characteristics of present-day glaciers located on the Koryaksky volcano. The results of fieldwork (2008–2009 and high-resolution satellite image analysis let us to specify and complete information on modern glacial complex of Koryaksky volcano. Now there are seven glaciers with total area 8.36 km2. Three of them advance, two are in stationary state and one degrades. Moreover, the paper describes the new crater glacier.

  2. Continuous monitoring of Hawaiian volcanoes with thermal cameras

    Science.gov (United States)

    Patrick, Matthew R.; Orr, Tim R.; Antolik, Loren; Lee, Robert Lopaka; Kamibayashi, Kevan P.

    2014-01-01

    Continuously operating thermal cameras are becoming more common around the world for volcano monitoring, and offer distinct advantages over conventional visual webcams for observing volcanic activity. Thermal cameras can sometimes “see” through volcanic fume that obscures views to visual webcams and the naked eye, and often provide a much clearer view of the extent of high temperature areas and activity levels. We describe a thermal camera network recently installed by the Hawaiian Volcano Observatory to monitor Kīlauea’s summit and east rift zone eruptions (at Halema‘uma‘u and Pu‘u ‘Ō‘ō craters, respectively) and to keep watch on Mauna Loa’s summit caldera. The cameras are long-wave, temperature-calibrated models protected in custom enclosures, and often positioned on crater rims close to active vents. Images are transmitted back to the observatory in real-time, and numerous Matlab scripts manage the data and provide automated analyses and alarms. The cameras have greatly improved HVO’s observations of surface eruptive activity, which includes highly dynamic lava lake activity at Halema‘uma‘u, major disruptions to Pu‘u ‘Ō‘ō crater and several fissure eruptions.

  3. Analysis of he laser performance of Tm3+,Tb3+(Ho3+):YVO4 crystals at~1.5μm wavelength

    Institute of Scientific and Technical Information of China (English)

    黄莉蕾; 付晏彬; 邬良能

    2003-01-01

    The absorption spectra of Tb,Tm:YVO4 and Ho,Tm:YVO4 are measured. The radiant and non-radiant transition probabilities from higher level to lower level, Ai,j and ?i,j, and the cross-relaxation probability are calculated in virtue of Judd-Ofelt and Dexter theories. The fluorescence lifetime of Tm3+ in the Tb3+ (or Ho3+) co-doped crystal is calculated. It indicates that the lifetime of initial level 3H4 of the laser transition can be shorter than that of terminal level 3F4 of the transition if the atomic percentage of Tb3+ (or Ho3+) ions is bigger than about 1 at%: namely, by means of the co-doping Tb3+ (or Ho3+) ions the self-termination phenomenon of laser light can be eliminated. Inserting the optic parameters to the formula deduced here on the laser threshold power Pth(4) and the slope efficiency ?s(4) of the four-energy-level system, we obtain the relationship of threshold power Pth(4) to the concentration of Tm3+ ions and discuss the effect of Tb3+ (or Ho3+) ion concentration on the laser threshold power Pth(4) around 1.5?m wavelength. The result shows that Tb,Tm:YVO4 crystal is a better choice to make the laser at ~1.5?m wavelength than Ho,Tm:YVO4crystal. We give the appropriate composition of (1-2) at% Tb, (1-2) at% Tm:YVO4, just for reference.

  4. Byurakan Astrophysical Observatory

    Science.gov (United States)

    Mickaelian, A. M.

    2016-09-01

    This booklet is devoted to NAS RA V. Ambartsumian Byurakan Astrophysical Observatory and is aimed at people interested in astronomy and BAO, pupils and students, BAO visitors and others. The booklet is made as a visiting card and presents concise and full information about BAO. A brief history of BAO, the biography of the great scientist Viktor Ambartsumian, brief biographies of 13 other deserved scientists formerly working at BAO (B.E. Markarian, G.A. Gurzadyan, L.V. Mirzoyan, M.A. Arakelian, et al.), information on BAO telescopes (2.6m, 1m Schmidt, etc.) and other scientific instruments, scientific library and photographic plate archive, Byurakan surveys (including the famous Markarian Survey included in the UNESCO Memory of the World International Register), all scientific meetings held in Byurakan, international scientific collaboration, data on full research staff of the Observatory, as well as former BAO researchers, who have moved to foreign institutions are given in the booklet. At the end, the list of the most important books published by Armenian astronomers and about them is given.

  5. Mahukona: The missing Hawaiian volcano

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M.O.; Muenow, D.W. (Univ. of Hawaii, Honolulu (USA)); Kurz, M.D. (Woods Hole Oceanographic Institution, MA (USA))

    1990-11-01

    New bathymetric and geochemical data indicate that a seamount west of the island of Hawaii, Mahukona, is a Hawaiian shield volcano. Mahukona has weakly alkalic lavas that are geochemically distinct. They have high {sup 3}He/{sup 4}He ratios (12-21 times atmosphere), and high H{sub 2}O and Cl contents, which are indicative of the early state of development of Hawaiian volcanoes. The He and Sr isotopic values for Mahukona lavas are intermediate between those for lavas from Loihi and Manuna Loa volcanoes and may be indicative of a temporal evolution of Hawaiian magmas. Mahukona volcano became extinct at about 500 ka, perhaps before reaching sea level. It fills the previously assumed gap in the parallel chains of volcanoes forming the southern segment of the Hawaiian hotspot chain. The paired sequence of volcanoes was probably caused by the bifurcation of the Hawaiian mantle plume during its ascent, creating two primary areas of melting 30 to 40 km apart that have persisted for at least the past 4 m.y.

  6. The Volcano Disaster Assistance Program (VDAP) - Past and Future

    Science.gov (United States)

    Ewert, J. W.; Pallister, J. S.

    2010-12-01

    For 24 years the U.S. Geological Survey and USAID’s Office of Foreign Disaster Assistance have supported a small team of scientists and the monitoring equipment required to respond to volcanic crises at short notice anywhere in the world. This VDAP team was founded following the 1985 tragedy at Nevado del Ruiz, where 23,000 perished following an eruption-triggered lahar that swept through the town of Armero, Colombia. Through its first two decades, VDAP has deployed teams and equipment to assist host-country counterparts in responding to volcanic eruptions and unrest at numerous volcanoes in Central and South America, the Caribbean, the Western Pacific and Africa and the Middle East. VDAP and the larger USGS Volcano Hazards Program (VHP) have a synergistic relationship. VDAP contributes to domestic eruption responses (e.g., Anatahan, Commonwealth of the Marianas Islands (2003-05), Mount St. Helens (2004) and several Alaskan eruptions). In turn, when VDAP lacks sufficient capability, the larger USGS Volcano Hazards Program provides a “backstop” of staff and expertise to support its international work. Between crises, VDAP conducts capacity-building projects, including construction of volcano-monitoring networks and education programs in monitoring, hazard assessment and eruption forecasting. Major capacity-building projects have focused on Central and South America (1998-present), Papua New Guinea (1998-2000) and Indonesia (2004-present). In all cases, VDAP scientists work in the background, providing support to counterpart agencies and representing the U.S. Government as scientist-diplomats. All VDAP monitoring equipment (whether used in crisis response or in capacity building) is donated to counterpart agencies as a form of U.S. foreign aid. Over the years, VDAP has helped build and sustain volcano observatories and monitoring programs in more than a dozen countries. As observatories, monitoring networks, and the science of volcanology and forecasting have

  7. Geophysical data collection using an interactive personal computer system. Part 1. ; Experimental monitoring of Suwanosejima volcano

    Energy Technology Data Exchange (ETDEWEB)

    Iguchi, M. (Kyoto Univerdity, Kyoto (Japan). Disaster Prevention Reserach Institute)

    1991-10-15

    In the article, a computer-communication system was developed in order to collect geophysical data from remote volcanos via a public telephpne network. This system is composed of a host presonal computer at an observatory and several personal computers as terminals at remote stations. Each terminal acquires geophysical data, such as seismic, intrasonic, and ground deformation date. These gara are stored in the terminals temporarily, and transmitted to the host computer upon command from host computer. Experimental monitoring was conducted between Sakurajima Volcanological Observatory and several statins in the Satsunan Islands and southern Kyushu. The seismic and eruptive activities of Suwanosejima volcano were monitored by this system. Consequently, earthquakes and air-shocks accompanied by the explosive activity were observed. B-type earthquakes occurred prio to the relatively prolonged eruptive activity. Intermittent occurrences of volcanic tremors were also clearly recognized from the change in mean amplitubes of seismic waves. 7 refs., 10 figs., 2 tabs.

  8. Stratospheric Observatory for Infrared Astronomy

    CERN Document Server

    Hamidouche, M; Marcum, P; Krabbe, A

    2010-01-01

    We present one of the new generations of observatories, the Stratospheric Observatory For Infrared Astronomy (SOFIA). This is an airborne observatory consisting of a 2.7-m telescope mounted on a modified Boeing B747-SP airplane. Flying at an up to 45,000 ft (14 km) altitude, SOFIA will observe above more than 99 percent of the Earth's atmospheric water vapor allowing observations in the normally obscured far-infrared. We outline the observatory capabilities and goals. The first-generation science instruments flying on board SOFIA and their main astronomical goals are also presented.

  9. Using seismic and tilt measurements simultaneously to forecast eruptions of silicic volcanoes

    Science.gov (United States)

    Neuberg, Jurgen; Collinson, Amy; Mothes, Patricia

    2016-04-01

    Independent interpretations of seismic swarms and tilt measurement on active silicic volcanoes have been successfully used to assess their eruption potential. Swarms of low-frequency seismic events have been associated with brittle failure or stick-slip motion of magma during ascent and have been used to estimate qualitatively the magma ascent rate which typically accelerates before lava dome collapses. Tilt signals are extremely sensitive indicators for volcano deformation and have been often modelled and interpreted as inflation or deflation of a shallow magma reservoir. Here we show that tilt in many cases does not represent inflation or deflation but is directly linked to magma ascent rate.This talk aims to combine these two independent observations, seismicity and deformation, to design and implement a forecasting tool that can be deployed in volcano observatories on an operational level.

  10. Eruption of a deep-sea mud volcano triggers rapid sediment movement.

    Science.gov (United States)

    Feseker, Tomas; Boetius, Antje; Wenzhöfer, Frank; Blandin, Jerome; Olu, Karine; Yoerger, Dana R; Camilli, Richard; German, Christopher R; de Beer, Dirk

    2014-11-11

    Submarine mud volcanoes are important sources of methane to the water column. However, the temporal variability of their mud and methane emissions is unknown. Methane emissions were previously proposed to result from a dynamic equilibrium between upward migration and consumption at the seabed by methane-consuming microbes. Here we show non-steady-state situations of vigorous mud movement that are revealed through variations in fluid flow, seabed temperature and seafloor bathymetry. Time series data for pressure, temperature, pH and seafloor photography were collected over 431 days using a benthic observatory at the active Håkon Mosby Mud Volcano. We documented 25 pulses of hot subsurface fluids, accompanied by eruptions that changed the landscape of the mud volcano. Four major events triggered rapid sediment uplift of more than a metre in height, substantial lateral flow of muds at average velocities of 0.4 m per day, and significant emissions of methane and CO₂ from the seafloor.

  11. "Mediterranean volcanoes vs. chain volcanoes in the Carpathians"

    Science.gov (United States)

    Chivarean, Radu

    2017-04-01

    Volcanoes have always represent an attractive subject for students. Europe has a small number of volcanoes and Romania has none active ones. The curricula is poor in the study of volcanoes. We want to make a parallel between the Mediterranean active volcanoes and the old extinct ones in the Oriental Carpathians. We made an comparison of the two regions in what concerns their genesis, space and time distribution, the specific relief and the impact in the landscape, consequences of their activities, etc… The most of the Mediterranean volcanoes are in Italy, in the peninsula in Napoli's area - Vezuviu, Campi Flegrei, Puzzoli, volcanic islands in Tirenian Sea - Ischia, Aeolian Islands, Sicily - Etna and Pantelleria Island. Santorini is located in Aegean Sea - Greece. Between Sicily and Tunisia there are 13 underwater volcanoes. The island called Vulcano, it has an active volcano, and it is the origin of the word. Every volcano in the world is named after this island, just north of Sicily. Vulcano is the southernmost of the 7 main Aeolian Islands, all volcanic in origin, which together form a small island arc. The cause of the volcanoes appears to be a combination of an old subduction event and tectonic fault lines. They can be considered as the origin of the science of volcanology. The volcanism of the Carpathian region is part of the extensive volcanic activity in the Mediterranean and surrounding regions. The Carpathian Neogene/Quaternary volcanic arc is naturally subdivided into six geographically distinct segments: Oas, Gutai, Tibles, Calimani, Gurghiu and Harghita. It is located roughly between the Carpathian thrust-and-fold arc to the east and the Transylvanian Basin to the west. It formed as a result of the convergence between two plate fragments, the Transylvanian micro-plate and the Eurasian plate. Volcanic edifices are typical medium-sized andesitic composite volcanoes, some of them attaining the caldera stage, complicated by submittal or peripheral domes

  12. Running a distributed virtual observatory: US Virtual Astronomical Observatory operations

    CERN Document Server

    McGlynn, Thomas A; Berriman, G Bruce; Thakar, Aniruddha R

    2012-01-01

    Operation of the US Virtual Astronomical Observatory shares some issues with modern physical observatories, e.g., intimidating data volumes and rapid technological change, and must also address unique concerns like the lack of direct control of the underlying and scattered data resources, and the distributed nature of the observatory itself. In this paper we discuss how the VAO has addressed these challenges to provide the astronomical community with a coherent set of science-enabling tools and services. The distributed nature of our virtual observatory-with data and personnel spanning geographic, institutional and regime boundaries-is simultaneously a major operational headache and the primary science motivation for the VAO. Most astronomy today uses data from many resources. Facilitation of matching heterogeneous datasets is a fundamental reason for the virtual observatory. Key aspects of our approach include continuous monitoring and validation of VAO and VO services and the datasets provided by the commun...

  13. LCOGT Network Observatory Operations

    CERN Document Server

    Pickles, Andrew; Boroson, Todd; Burleson, Ben; Conway, Patrick; de Vera, Jon; Elphick, Mark; Haworth, Brian; Rosing, Wayne; Saunders, Eric; Thomas, Doug; White, Gary; Willis, Mark; Walker, Zach

    2014-01-01

    We describe the operational capabilities of the Las Cumbres Observatory Global Telescope Network. We summarize our hardware and software for maintaining and monitoring network health. We focus on methodologies to utilize the automated system to monitor availability of sites, instruments and telescopes, to monitor performance, permit automatic recovery, and provide automatic error reporting. The same jTCS control system is used on telescopes of apertures 0.4m, 0.8m, 1m and 2m, and for multiple instruments on each. We describe our network operational model, including workloads, and illustrate our current tools, and operational performance indicators, including telemetry and metrics reporting from on-site reductions. The system was conceived and designed to establish effective, reliable autonomous operations, with automatic monitoring and recovery - minimizing human intervention while maintaining quality. We illustrate how far we have been able to achieve that.

  14. The Virtual Observatory Registry

    CERN Document Server

    Demleitner, Markus; Sidaner, Pierre Le; Plante, Raymond L

    2014-01-01

    In the Virtual Observatory (VO), the Registry provides the mechanism with which users and applications discover and select resources -- typically, data and services -- that are relevant for a particular scientific problem. Even though the VO adopted technologies in particular from the bibliographic community where available, building the Registry system involved a major standardisation effort, involving about a dozen interdependent standard texts. This paper discusses the server-side aspects of the standards and their application, as regards the functional components (registries), the resource records in both format and content, the exchange of resource records between registries (harvesting), as well as the creation and management of the identifiers used in the system based on the notion of authorities. Registry record authors, registry operators or even advanced users thus receive a big picture serving as a guideline through the body of relevant standard texts. To complete this picture, we also mention comm...

  15. The virtual observatory registry

    Science.gov (United States)

    Demleitner, M.; Greene, G.; Le Sidaner, P.; Plante, R. L.

    2014-11-01

    In the Virtual Observatory (VO), the Registry provides the mechanism with which users and applications discover and select resources-typically, data and services-that are relevant for a particular scientific problem. Even though the VO adopted technologies in particular from the bibliographic community where available, building the Registry system involved a major standardisation effort, involving about a dozen interdependent standard texts. This paper discusses the server-side aspects of the standards and their application, as regards the functional components (registries), the resource records in both format and content, the exchange of resource records between registries (harvesting), as well as the creation and management of the identifiers used in the system based on the notion of authorities. Registry record authors, registry operators or even advanced users thus receive a big picture serving as a guideline through the body of relevant standard texts. To complete this picture, we also mention common usage patterns and open issues as appropriate.

  16. The Sudbury Neutrino Observatory

    Science.gov (United States)

    Bellerive, A.; Klein, J. R.; McDonald, A. B.; Noble, A. J.; Poon, A. W. P.

    2016-07-01

    This review paper provides a summary of the published results of the Sudbury Neutrino Observatory (SNO) experiment that was carried out by an international scientific collaboration with data collected during the period from 1999 to 2006. By using heavy water as a detection medium, the SNO experiment demonstrated clearly that solar electron neutrinos from 8B decay in the solar core change into other active neutrino flavors in transit to Earth. The reaction on deuterium that has equal sensitivity to all active neutrino flavors also provides a very accurate measure of the initial solar flux for comparison with solar models. This review summarizes the results from three phases of solar neutrino detection as well as other physics results obtained from analyses of the SNO data.

  17. The Sudbury Neutrino Observatory

    CERN Document Server

    Bellerive, A; McDonald, A B; Noble, A J; Poon, A W P

    2016-01-01

    This review paper provides a summary of the published results of the Sudbury Neutrino Observatory (SNO) experiment that was carried out by an international scientific collaboration with data collected during the period from 1999 to 2006. By using heavy water as a detection medium, the SNO experiment demonstrated clearly that solar electron neutrinos from $^8$B decay in the solar core change into other active neutrino flavors in transit to Earth. The reaction on deuterium that has equal sensitivity to all active neutrino flavors also provides a very accurate measure of the initial solar flux for comparison with solar models. This review summarizes the results from three phases of solar neutrino detection as well as other physics results obtained from analyses of the SNO data.

  18. Comparison of Superconducting and Spring Gravimeters at the Mizusawa VLBI Observatory of the National Astronomical Observatory of Japan

    Science.gov (United States)

    Miura, Satoshi; Ikeda, Hiroshi; Kim, Tae-Hee; Tamura, Yoshiaki

    2017-04-01

    Continuous microgravity monitoring is utilized to gain new insights into changes in the subsurface distribution of magma and/or fluid that commonly occur beneath active volcanoes. Rather new superconducting and spring gravimeters, iGrav#003 and gPhone#136 are collocated with a superconducting gravimeter, TT#70 at the Mizusawa VLBI Observatory of the National Astronomical Observatory of Japan, since the end of September, 2016 in order to evaluate those performances before field deployment planned in 2017. Calibration of iGrav#003 was carried out by collocation with an absolute gravimeter FG5 of the Earthquake Research Institute, University of Tokyo (Okubo, 2016, personal comm.) at a Fundamental Gravity Station in Sendai in July, 2016. Based on the scale factors of iGrav#003 obtained by the calibration and of gPhone#136 provided by the manufacturer (Micro-g LaCoste, Inc.), tidal analyses are performed by means of BAYTAP-G (Tamura et al., 1991, GJI). Amplitudes and phases of each major tidal constituent mutually agree well within ±4 % and ±3 degrees, respectively. The instrumental drift rate of iGrav#003 is very low, about 5 micro-Gal/month, whereas that of gPhone#136 is very high, about 500 micro-Gal/month. The high drift rate of gPhone#136, however, is well approximated by a quadratic function at present and can be removed. The detrended time series of gPhone#136 shows good agreement with iGrav#003 time series in the overall feature: gravity fluctuations with amplitudes of about a few micro-Gal and with durations of a few days, which may be due to variations in the moisture content of the topmost unsaturated sedimentary layer and the water table height. It suggests that both instruments may capture volcanic signals associated with pressure changes in magma chambers, dike intrusion/withdrawing, and so on. iGrav#003 will be installed in the Zao volcanological observatory of Tohoku University located at about 3 km from the summit crater, and gPhone#136 will be

  19. Rolloff Roof Observatory Construction (Abstract)

    Science.gov (United States)

    Ulowetz, J. H.

    2015-12-01

    (Abstract only) Lessons learned about building an observatory by someone with limited construction experience, and the advantages of having one for imaging and variable star studies. Sample results shown of composite light curves for cataclysmic variables UX UMa and V1101 Aql with data from my observatory combined with data from others around the world.

  20. Space Research in Baldone Observatory

    Directory of Open Access Journals (Sweden)

    Eglitis, I.

    2017-01-01

    Full Text Available The Baldone observatory deals with the U-, B-, V-, R-, I-photometry and low resolution spectroscopy of carbon stars, the monitoring of small bodies of Solar system, and with the digitizing and processing of 24 300 plates from the Schmidt wide field telescope archive. The astronomers from the observatory are working to popularize astronomy.

  1. 21W、56MHz Nd∶YVO4皮秒脉冲激光放大器%Research on 21 W and 56 MHz Nd∶YVO4 Picosecond Pulse Laser

    Institute of Scientific and Technical Information of China (English)

    麻云凤; 余锦; 牛岗; 张晶; 赵天卓; 闫莹; 张雪; 樊仲维

    2013-01-01

    Three power amplifier system is reported in which the Nd! YVO4 crystal is pumped by laser diode (LD), in which 1064 nm picosecond laser output average power is more than 21 W. When the repetition frequency of 56 MHz, the average power of 3 W picosecond seed pulse is injected, a maximum power of 26 W is got by a three-stage power amplifier system with the optical conversion efficiency of 25%. The picosecond pulse duration is less than 17 ps, power instability in 1 h is less than 2% , and the light beam quality M2 is less than 1.5. A RbTiOPO, (RTP) electro-optical switch is as a marking switch and the main-minor pulse ratio is up to 210: 1, which is suitable for the use of the marking machine.%报道了通过激光二极管(LD)单端抽运Nd∶ YVO4晶体的三级功率放大系统,获得稳定的平均功率21 W以上的1064 nm皮秒激光输出.当重复频率为56 MHz、平均功率为4W的皮秒种子脉冲注入时,经过三级功率放大,最高功率达26W,光-光转换效率达25%.皮秒单脉冲宽度为17 ps,连续1h内的功率不稳定性小于2%,光束质量M2为1.5.采用RbTiOPO4(RTP)电光开关作为打标开关,实现主从脉冲比达210∶1以上,可以满足打标机的需要.

  2. Mud Volcanoes Formation And Occurrence

    Science.gov (United States)

    Guliyev, I. S.

    2007-12-01

    Mud volcanoes are natural phenomena, which occur throughout the globe. They are found at a greater or lesser scale in Azerbaijan, Turkmenistan, Georgia, on the Kerch and Taman peninsulas, on Sakhalin Island, in West Kuban, Italy, Romania, Iran, Pakistan, India, Burma, China, Japan, Indonesia, Malaysia, New Zealand, Mexico, Colombia, Trinidad and Tobago, Venezuela and Ecuador. Mud volcanoes are most well-developed in Eastern Azerbaijan, where more than 30% of all the volcanoes in the world are concentrated. More than 300 mud volcanoes have already been recognized here onshore or offshore, 220 of which lie within an area of 16,000 km2. Many of these mud volcanoes are particularly large (up to 400 m high). The volcanoes of the South Caspian form permanent or temporary islands, and numerous submarine banks. Many hypotheses have been developed regarding the origin of mud volcanoes. Some of those hypotheses will be examined in the present paper. Model of spontaneous excitation-decompaction (proposed by Ivanov and Guliev, 1988, 2002). It is supposed that one of major factors of the movement of sedimentary masses and formation of hydrocarbon deposits are phase transitions in sedimentary basin. At phase transitions there are abnormal changes of physical and chemical parameters of rocks. Abnormal (high and negative) pressure takes place. This process is called as excitation of the underground environment with periodicity from several tens to several hundreds, or thousand years. The relationship between mud volcanism and the generation of hydrocarbons, particularly methane, is considered to be a critical factor in mud volcano formation. At high flow rates the gas and sediment develops into a pseudo-liquid state and as flow increases the mass reaches the "so-called hover velocity" where mass transport begins. The mass of fluid moves as a quasi-uniform viscous mass through the sediment pile in a piston like manner until expelled from the surface as a "catastrophic eruption

  3. Ancient "Observatories" - A Relevant Concept?

    Science.gov (United States)

    Belmonte, Juan Antonio

    It is quite common, when reading popular books on astronomy, to see a place referred to as "the oldest observatory in the world". In addition, numerous books on archaeoastronomy, of various levels of quality, frequently refer to the existence of "prehistoric" or "ancient" observatories when describing or citing monuments that were certainly not built with the primary purpose of observing the skies. Internet sources are also guilty of this practice. In this chapter, the different meanings of the word observatory will be analyzed, looking at how their significances can be easily confused or even interchanged. The proclaimed "ancient observatories" are a typical result of this situation. Finally, the relevance of the concept of the ancient observatory will be evaluated.

  4. High power red laser at 671nm by intracavity frequency doubling of a Nd:YVO4 laser

    Institute of Scientific and Technical Information of China (English)

    Yao Ai-Yun; Hou Wei; Li Hui-Qing; Bi Yong; Li Rui-Ning; Geng Ai-Cong; Kong Yu-Peng; Cui Da-Fu; Xu Zu-Yan

    2005-01-01

    This paper reports a high-power quasi-continuous wave (quasi-CW) source of red laser at 671nm obtained by intracavity frequency doubling of a double-end-pumped 1342nm Nd:YVO4 laser, based on the nonlinear crystal LiB3O5 (LBO)The average output power of 2.9W at 671nm was obtained at the incident pump power of 19.5W. The overall optical to optical efficiency is 14.9%. We have analyzed the influence of the optimal pump size, the optimal focal position and the reduction of the thermal effect on high output. The combination of double-end-pumping and the quasi-CW performance greatly reduces the thermal effect.

  5. The Study on the Interaction between Tm3+ and Tb3+ Rare Earth Ions in YVO4 Crystal

    Institute of Scientific and Technical Information of China (English)

    HUANG Lilei; HONG Zhi; ZHUANG Jian

    2001-01-01

    In this paper the measurement result of transmission spectrum of Tb,Tm∶YVO4 is presented. The intensity Ωt, the probabilities of radiating transition, non-radiating transition, the cross-relaxation and the lifetimes of Tm3+ ions at 3H4 and 3F4 levels are calculated. The results show that when the concentration of Tm3+ ions >1.2 at.-%, the fluorescent lifetime of upper level 3H4 is shorter than that of lower level 3F4 due to the interaction between Tm3+ and Tb3+ ions, thus the lasing self-termination at ~1.5 μm can be eliminated.

  6. Highly efficient cascaded P-doped Raman fiber laser pumped by Nd:YVO4 solid-state laser

    Institute of Scientific and Technical Information of China (English)

    Chaohong Huang; Zhiping Cai; Zhengqian Luo; Wencai Huang; Huiying Xu; Chenchun Ye

    2008-01-01

    A highly efficient cascaded P-doped Raman fiber laser (RFL) pumped by a 1064-nm continuous wave (CW) Nd:YVO4 solid-state laser is reported. 1.15-W CW output power at 1484 nm is obtained while the input pump power is 4 W, corresponding to the power conversion efficiency of 28.8%. The threshold pump power for the second-order Stokes radiation is 1.13 W. The slope efficiency is as high as 42.6%. The experimental results are in good agreement with theoretical ones. Furthermore, the power instability of the P-doped RFL at 1484 nm in an hour is observed to be less than 5%.

  7. Beam quality management by periodic reproduction of wavefront aberrations in end-pumped Nd:YVO4 laser amplifiers.

    Science.gov (United States)

    Liu, Bin; Liu, Chong; Shen, Lifeng; Wang, Chunhua; Ye, Zhibin; Liu, Dong; Xiang, Zhen

    2016-04-18

    A method for beam quality management is presented in a master oscillator power amplifier (MOPA) using Nd:YVO4 as the gain medium by extra-cavity periodic reproduction of wavefront aberrations. The wavefront aberration evolution of the intra-cavity beams is investigated for both symmetrical and asymmetrical resonators. The wavefront aberration reproduction process is successfully realized outside the cavity in four-stage amplifiers. In the MOPA with a symmetrical oscillator, the laser power increases linearly and the beam quality hardly changes. In the MOPA with an asymmetrical oscillator, the beam quality is deteriorated after the odd-stage amplifier and is improved after the even-stage amplifier. The wavefront aberration reproduction during the extra-cavity beam propagation in the amplifiers is equivalent to that during the intra-cavity propagation. This solution helps to achieve the effective beam quality management in laser amplifier chains.

  8. The Sudbury Neutrino Observatory

    Science.gov (United States)

    Ewan, G. T.

    1992-04-01

    The Sudbury Neutrino Observatory (SNO) detector is a 1000 ton heavy water (D2O) Cherenkov detector designed to study neutrinos from the sun and other astrophysical sources. The use of heavy water allows both electron neutrinos and all other types of neutrinos to be observed by three complementary reactions. The detector will be sensitive to the electron neutrino flux and energy spectrum shape and to the total neutrino flux irrespective of neutrino type. These measurements will provide information on both vacuum neutrino oscillations and matter-enhanced oscillations, the MSW effect. In the event of a supernova it will be very sensitive to muon and tau neutrinos as well as the electron neutrinos emitted in the initial burst, enabling sensitive mass measurements as well as providing details of the physics of stellar collapse. On behalf of the Sudbury Neutrino Observatory (SNO) Collaboration : H.C . Evans, G.T . Ewan, H.W. Lee, J .R . Leslie, J .D. MacArthur, H .-B . Mak, A.B . McDonald, W. McLatchie, B.C . Robertson, B. Sur, P. Skensved (Queen's University) ; C.K . Hargrove, H. Mes, W.F. Davidson, D. Sinclair, 1 . Blevis, M. Shatkay (Centre for Research in Particle Physics) ; E.D. Earle, G.M. Milton, E. Bonvin, (Chalk River Laboratories); J .J . Simpson, P. Jagam, J . Law, J .-X . Wang (University of Guelph); E.D . Hallman, R.U. Haq (Laurentian University); A.L. Carter, D. Kessler, B.R . Hollebone (Carleton University); R. Schubank . C.E . Waltha m (University of British Columbia); R.T. Kouzes, M.M. Lowry, R.M. Key (Princeton University); E.W. Beier, W. Frati, M. Newcomer, R. Van Berg (University of Penn-sylvania), T.J . Bowles, P.J . Doe, S.R . Elliott, M.M. Fowler, R.G.H. Robertson, D.J . Vieira, J .B . Wilhelmy, J .F. Wilker-son, J .M. Wouters (Los Alamos National Laboratory) ; E. Norman, K. Lesko, A. Smith, R. Fulton, R. Stokstad (Lawrence Berkeley Laboratory), N.W. Tanner, N. JCIILY, P. Trent, J . Barton, D.L . Wark (University of Oxford).

  9. Nd:YVO{sub 4} laser removal of graffiti from granite. Influence of paint and rock properties on cleaning efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Rivas, T., E-mail: trivas@uvigo.es [Dpto. Ingenieria de los Recursos Naturales y Medio Ambiente. Universidad de Vigo, Lagoas-Marcosende s/n, 36310 Vigo (Spain); Pozo, S. [Dpto. Ingenieria de los Recursos Naturales y Medio Ambiente. Universidad de Vigo, Lagoas-Marcosende s/n, 36310 Vigo (Spain); Fiorucci, M.P.; Lopez, A.J.; Ramil, A. [Centro de Investigacions Tecnoloxicas (CIT), Universidade da Coruna, 15403 Ferrol (Spain)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Cleaning using NdYVO{sub 4} laser at 355 nm of four different graffiti colours applied on granites. Black-Right-Pointing-Pointer Analysis of the influence of paint composition and properties of rocks on the process. Black-Right-Pointing-Pointer Composition of the paints and, in turn reflectance, determine the removal effectiveness. Black-Right-Pointing-Pointer The laser removal is not conditioned by properties of the stones. - Abstract: This paper presents the cleaning efficiency results for four differently coloured graffiti paints applied to two types of granitic stone by Nd:YVO{sub 4} laser at 355 nm. The paints were characterized in terms of mineralogy and chemistry using x-ray fluorescence, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM); paint absorbance in the ultraviolet-visible-infrared range (200-2000 nm) was also assessed. The studied granites had different mineralogy, texture and porosity properties. Cleaning efficiency was evaluated by polarized microscopy, SEM, FTIR spectroscopy and spectrophotometer colour measurements. The results indicate differences in the effectiveness of surface cleaning for the blue, red and black paints as opposed to the silver paint, mainly attributed to chemical composition. No evidence was found that the granite properties had a bearing on laser effectiveness, although the degree, type and spatial distribution of transgranular fissures in the stone affected the overall assessment of cleaning effectiveness. Polarized light microscopy observations and colour measurements showed that the intensity and distribution of fissures affect the depth of paint penetration, ultimately affecting the cleaning efficiency for both granites.

  10. Remote Sensing of Active Volcanoes

    Science.gov (United States)

    Francis, Peter; Rothery, David

    The synoptic coverage offered by satellites provides unparalleled opportunities for monitoring active volcanoes, and opens new avenues of scientific inquiry. Thermal infrared radiation can be used to monitor levels of activity, which is useful for automated eruption detection and for studying the emplacement of lava flows. Satellite radars can observe volcanoes through clouds or at night, and provide high-resolution topographic data. In favorable conditions, radar inteferometery can be used to measure ground deformation associated with eruptive activity on a centimetric scale. Clouds from explosive eruptions present a pressing hazard to aviation; therefore, techniques are being developed to assess eruption cloud height and to discriminate between ash and meterological clouds. The multitude of sensors to be launched on future generations of space platforms promises to greatly enhance volcanological studies, but a satellite dedicated to volcanology is needed to meet requirements of aviation safety and volcano monitoring.

  11. Mount Rainier: A decade volcano

    Science.gov (United States)

    Swanson, Donald A.; Malone, Stephen D.; Samora, Barbara A.

    Mount Rainier, the highest (4392 m) volcano in the Cascade Range, towers over a population of more than 2.5 million in the Seattle-Tacoma metropolitan area, and its drainage system via the Columbia River potentially affects another 500,000 residents of southwestern Washington and northwestern Oregon (Figure 1). Mount Rainier is the most hazardous volcano in the Cascades in terms of its potential for magma-water interaction and sector collapse. Major eruptions, or debris flows even without eruption, pose significant dangers and economic threats to the region. Despite such hazard and risk, Mount Rainier has received little study; such important topics as its petrologic and geochemical character, its proximal eruptive history, its susceptibility to major edifice failure, and its development over time have been barely investigated. This situation may soon change because of Mount Rainier's recent designation as a “Decade Volcano.”

  12. Scientific verification of High Altitude Water Cherenkov observatory

    Energy Technology Data Exchange (ETDEWEB)

    Marinelli, Antonio, E-mail: antonio.marinelli@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, Mexico D.F. (Mexico); Sparks, Kathryne [Department of Physics, Pennsylvania State University, University Park, PA (United States); Alfaro, Ruben [Instituto de Física, Universidad Nacional Autónoma de México, Mexico D.F. (Mexico); González, María Magdalena; Patricelli, Barbara; Fraija, Nissim [Instituto de Astronomia, Universidad Nacional Autónoma de México, Mexico D.F. (Mexico)

    2014-04-01

    The High Altitude Water Cherenkov (HAWC) observatory is a TeV gamma-ray and cosmic-ray detector currently under construction at an altitude of 4100 m close to volcano Sierra Negra in the state of Puebla, Mexico. The HAWC [1] observatory is an extensive air-shower array composed of 300 optically isolated water Cherenkov detectors (WCDs). Each WCD contains ∼200,000 l of filtered water and four upward-facing photomultiplier tubes. In Fall 2014, when the HAWC observatory will reach an area of 22,000 m{sup 2}, the sensitivity will be 15 times higher than its predecessor Milagro [2]. Since September 2012, more than 30 WCDs have been instrumented and taking data. This first commissioning phase has been crucial for the verification of the data acquisition and event reconstruction algorithms. Moreover, with the increasing number of instrumented WCDs, it is important to verify the data taken with different configuration geometries. In this work we present a comparison between Monte Carlo simulation and data recorded by the experiment during 24 h of live time between 14 and 15 April of 2013 when 29 WCDs were active.

  13. Scientific verification of High Altitude Water Cherenkov observatory

    Science.gov (United States)

    Marinelli, Antonio; Sparks, Kathryne; Alfaro, Ruben; González, María Magdalena; Patricelli, Barbara; Fraija, Nissim

    2014-04-01

    The High Altitude Water Cherenkov (HAWC) observatory is a TeV gamma-ray and cosmic-ray detector currently under construction at an altitude of 4100 m close to volcano Sierra Negra in the state of Puebla, Mexico. The HAWC [1] observatory is an extensive air-shower array composed of 300 optically isolated water Cherenkov detectors (WCDs). Each WCD contains ~200,000 l of filtered water and four upward-facing photomultiplier tubes. In Fall 2014, when the HAWC observatory will reach an area of 22,000 m2, the sensitivity will be 15 times higher than its predecessor Milagro [2]. Since September 2012, more than 30 WCDs have been instrumented and taking data. This first commissioning phase has been crucial for the verification of the data acquisition and event reconstruction algorithms. Moreover, with the increasing number of instrumented WCDs, it is important to verify the data taken with different configuration geometries. In this work we present a comparison between Monte Carlo simulation and data recorded by the experiment during 24 h of live time between 14 and 15 April of 2013 when 29 WCDs were active.

  14. Systematic radon survey over active volcanoes

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, J.L.; Monnin, M.; Garcia Vindas, J.R. [Centre National de la Recherche Cientifique, Montpellier (France). Lab. GBE; Ricard, L.P.; Staudacher, T. [Observatoire Volcanologique Du Pitou de la Fournaise, La Plaine des Cafres (France)

    1999-08-01

    Data obtained since 1993 on Costa Rica volcanos are presented and radon anomalies recorded before the eruption of the Irazu volcano (December 8, 1994) are discussed. The Piton de la Fournaise volcano is inactive since mid 1992. The influence of the external parameters on the radon behaviour is studied and the type of perturbations induced on short-term measurements are individuate.

  15. Computer aided detection of transient inflation events at Alaskan volcanoes using GPS measurements from 2005-2015

    Science.gov (United States)

    Li, Justin D.; Rude, Cody M.; Blair, David M.; Gowanlock, Michael G.; Herring, Thomas A.; Pankratius, Victor

    2016-11-01

    Analysis of transient deformation events in time series data observed via networks of continuous Global Positioning System (GPS) ground stations provide insight into the magmatic and tectonic processes that drive volcanic activity. Typical analyses of spatial positions originating from each station require careful tuning of algorithmic parameters and selection of time and spatial regions of interest to observe possible transient events. This iterative, manual process is tedious when attempting to make new discoveries and does not easily scale with the number of stations. Addressing this challenge, we introduce a novel approach based on a computer-aided discovery system that facilitates the discovery of such potential transient events. The advantages of this approach are demonstrated by actual detections of transient deformation events at volcanoes selected from the Alaska Volcano Observatory database using data recorded by GPS stations from the Plate Boundary Observatory network. Our technique successfully reproduces the analysis of a transient signal detected in the first half of 2008 at Akutan volcano and is also directly applicable to 3 additional volcanoes in Alaska, with the new detection of 2 previously unnoticed inflation events: in early 2011 at Westdahl and in early 2013 at Shishaldin. This study also discusses the benefits of our computer-aided discovery approach for volcanology in general. Advantages include the rapid analysis on multi-scale resolutions of transient deformation events at a large number of sites of interest and the capability to enhance reusability and reproducibility in volcano studies.

  16. 20.6 W Nd∶YVO4 Thin Disk Laser with Laser-Diode Direct Upper-State Pumping%20.6W激光二极管直接上能级抽运Nd∶YVO4薄片激光器

    Institute of Scientific and Technical Information of China (English)

    吴兴盛; 高健存; 唐新春; 王坤; 方茗; 王豫明; 曹有旺

    2012-01-01

    A 880 nm laser diode direct upper-state pumped Nd: YVO4 thin disk laser is demonstrated. With a 0. 3 mm thick Nd-doping concentration of 0. 5% Nd:YVO4 disk and pump power of 39. 3 W, 20. 6 W output power at 1064 nm is obtained and the optical-optical efficiency exceeds 50% .%使用自行搭建的24通抽运系统,实现了880 nm激光器二极管直接上能级抽运的Nd∶YVO4薄片激光器.采用厚度为0.3 mm、掺杂原子数分数为0.5%的Nd∶YVO4薄片晶体,在39.3W的抽运功率下获得了20.6W的1064 nm连续激光输出,光-光转换效率超过50%.

  17. Health Observatories in Iran

    Directory of Open Access Journals (Sweden)

    K Shad­pour

    2013-01-01

    Full Text Available Background: The Islamic Republic of Iran, in her 20 year vision by the year 2025, is a developed country with the first economic, scientific and technological status in the region, with revolutionary and Islamic identity, inspiring Islamic world, as well as effective and constructive interaction in international relations. Enjoying health, welfare, food security, social security, equal opportunities, fair income distribution, strong family structure; to be away from poverty, corruption, and discrimination; and benefiting desirable living environment are also considered out of characteristics of Iranian society in that year. Strategic leadership towards perceived vision in each setting requires restrictive, complete and timely information. According to constitution of National Institute for Health Researches, law of the Fifth Development Plan of the country and characteristics of health policy making, necessity of designing a Health Observatory System (HOS was felt. Some Principles for designing such system were formulated by taking following steps: reviewing experience in other countries, having local history of the HOS in mind, superior documents, analysis of current production and management of health information, taking the possibilities to run a HOS into account. Based on these principles, the protocol of HOS was outlined in 3 different stages of opinion poll of informed experts responsible for production on management of information, by using questionnaires and Focus Group Discussions. The protocol includes executive regulations, the list of health indicators, vocabulary and a calendar for periodic studies of the community health situation.

  18. The CTA Observatory

    CERN Document Server

    Wagner, R M; Sillanpää, A; Wagner, S; ),

    2009-01-01

    In recent years, ground-based very-high-energy (VHE; E>100 GeV) gamma-ray astronomy has experienced a major breakthrough with the impressive astrophysical results obtained mainly by the current generation experiments like H.E.S.S., MAGIC, MILAGRO and VERITAS. The ground-based Imaging Air Cherenkov Technique for detecting VHE gamma-rays has matured, and a fast assembly of inexpensive and robust telescopes is possible. The goal for the next generation of instruments is to increase their sensitivity by a factor >10 compared to current facilities, to extend the accessible gamma-ray energies from a few tens of GeV to a hundred TeV, and to improve on other parameters like the energy and angular resolution (improve the point-spread function by a factor 4-5 w.r.t. current instruments). The Cherenkov Telescope Array (CTA) project is an initiative to build the next generation ground-based gamma-ray instrument, will serve as an observatory to a wide astrophysics community. I discuss the key physics goals and resulting d...

  19. Health observatories in iran.

    Science.gov (United States)

    Rashidian, A; Damari, B; Larijani, B; Vosoogh Moghadda, A; Alikhani, S; Shadpour, K; Khosravi, A

    2013-01-01

    The Islamic Republic of Iran, in her 20 year vision by the year 2025, is a developed country with the first economic, scientific and technological status in the region, with revolutionary and Islamic identity, inspiring Islamic world, as well as effective and constructive interaction in international relations. Enjoying health, welfare, food security, social security, equal opportunities, fair income distribution, strong family structure; to be away from poverty, corruption, and discrimination; and benefiting desirable living environment are also considered out of characteristics of Iranian society in that year. Strategic leadership towards perceived vision in each setting requires restrictive, complete and timely information. According to constitution of National Institute for Health Researches, law of the Fifth Development Plan of the country and characteristics of health policy making, necessity of designing a Health Observatory System (HOS) was felt. Some Principles for designing such system were formulated by taking following steps: reviewing experience in other countries, having local history of the HOS in mind, superior documents, analysis of current production and management of health information, taking the possibilities to run a HOS into account. Based on these principles, the protocol of HOS was outlined in 3 different stages of opinion poll of informed experts responsible for production on management of information, by using questionnaires and Focus Group Discussions. The protocol includes executive regulations, the list of health indicators, vocabulary and a calendar for periodic studies of the community health situation.

  20. Expanding the HAWC Observatory

    Science.gov (United States)

    Mori, Johanna; HAWC Collaboration; College of Idaho; HAWC Collaboration

    2017-01-01

    To increase the effective area and sensitivity of the High Altitude Water Cherenkov Observatory to gamma-ray photons with energies higher than 10 TeV, we are building 350 smaller outrigger tanks around the main array of 300 existing tanks. HAWC detects cascades of charged particles (``extensive air showers'') created by TeV gamma rays hitting the atmosphere. Increasing the size of the array will improve the sensitivity of the array by a factor of 2 to 4 above 10 TeV, allowing for more accurate gamma-ray origin reconstruction and energy estimation. Building the outrigger array requires carefully calibrated equipment, including PMTs and high voltage signal cables of the correct length. Origin reconstruction relies on precise signal timing, so the signal cables' lengths were standardized so that the signal transit time varied by less than 5 ns. Energy estimation depends on accurate photon counts from each tank, so the PMTs were calibrated with a laser and filter wheels to give the PMTs a known amount of light.

  1. Hanohano: Hawaiian antineutrino observatory

    Energy Technology Data Exchange (ETDEWEB)

    Maricic, Jelena, E-mail: jelena@physics.drexel.ed [Drexel University, 3141 Chestnut St. 12-816, Philadelphia, PA, 19104 (United States)

    2010-01-01

    Design studies are underway for the deep ocean antineutrino observatory Hanohano. The 10 kton monolitic underwater detector will be able to make precision measurement of neutrino mixing parameters (including {theta}{sub 13} and neutrino mass hierarchy) if stationed around 60 km offshore, from the nuclear reactor. Hanohano will be a mobile detector and placing it in a mid-Pacific location will provide the first ever flux measurement of geoneutrinos (antineutrinos emitted in the radioactive decay series of uranium and thorium), coming from the Earth's mantle and perform a sensitivity search for a hypothetical natural fission reactor in the Earth's core. Additional deployment at a different mid-ocean location will lead to tests of lateral heterogeneity of uranium and thorium in the Earth's mantle. These measurements would provide an important insight into deep-Earth geophysics, mantle composition and understanding of the Earth's heat flow and sources of energy inside the Earth.

  2. Alaska volcanoes guidebook for teachers

    Science.gov (United States)

    Adleman, Jennifer N.

    2011-01-01

    Alaska’s volcanoes, like its abundant glaciers, charismatic wildlife, and wild expanses inspire and ignite scientific curiosity and generate an ever-growing source of questions for students in Alaska and throughout the world. Alaska is home to more than 140 volcanoes, which have been active over the last 2 million years. About 90 of these volcanoes have been active within the last 10,000 years and more than 50 of these have been active since about 1700. The volcanoes in Alaska make up well over three-quarters of volcanoes in the United States that have erupted in the last 200 years. In fact, Alaska’s volcanoes erupt so frequently that it is almost guaranteed that an Alaskan will experience a volcanic eruption in his or her lifetime, and it is likely they will experience more than one. It is hard to imagine a better place for students to explore active volcanism and to understand volcanic hazards, phenomena, and global impacts. Previously developed teachers’ guidebooks with an emphasis on the volcanoes in Hawaii Volcanoes National Park (Mattox, 1994) and Mount Rainier National Park in the Cascade Range (Driedger and others, 2005) provide place-based resources and activities for use in other volcanic regions in the United States. Along the lines of this tradition, this guidebook serves to provide locally relevant and useful resources and activities for the exploration of numerous and truly unique volcanic landscapes in Alaska. This guidebook provides supplemental teaching materials to be used by Alaskan students who will be inspired to become educated and prepared for inevitable future volcanic activity in Alaska. The lessons and activities in this guidebook are meant to supplement and enhance existing science content already being taught in grade levels 6–12. Correlations with Alaska State Science Standards and Grade Level Expectations adopted by the Alaska State Department of Education and Early Development (2006) for grades six through eleven are listed at

  3. Remote-controlled pan, tilt, zoom cameras at Kilauea and Mauna Loa Volcanoes, Hawai'i

    Science.gov (United States)

    Hoblitt, Richard P.; Orr, Tim R.; Castella, Frederic; Cervelli, Peter F.

    2008-01-01

    Lists of important volcano-monitoring disciplines usually include seismology, geodesy, and gas geochemistry. Visual monitoring - the essence of volcanology - is usually not mentioned. Yet, observations of the outward appearance of a volcano provide data that is equally as important as that provided by the other disciplines. The eye was almost certainly the first volcano monitoring-tool used by early man. Early volcanology was mostly descriptive and was based on careful visual observations of volcanoes. There is still no substitute for the eye of an experienced volcanologist. Today, scientific instruments replace or augment our senses as monitoring tools because instruments are faster and more sensitive, work tirelessly day and night, keep better records, operate in hazardous environments, do not generate lawsuits when damaged or destroyed, and in most cases are cheaper. Furthermore, instruments are capable of detecting phenomena that are outside the reach of our senses. The human eye is now augmented by the camera. Sequences of timed images provide a record of visual phenomena that occur on and above the surface of volcanoes. Photographic monitoring is a fundamental monitoring tool; image sequences can often provide the basis for interpreting other data streams. Monitoring data are most useful when they are generated and are available for analysis in real-time or near real-time. This report describes the current (as of 2006) system for real-time photograph acquisition and transmission from remote sites on Kilauea and Mauna Loa volcanoes to the U.S. Geological Survey Hawaiian Volcano Observatory (HVO). It also describes how the photographs are archived and analyzed. In addition to providing system documentation for HVO, we hope that the report will prove useful as a practical guide to the construction of a high-bandwidth network for the telemetry of real-time data from remote locations.

  4. Thermal precursors in satellite images of the 1999 eruption of Shishaldin Volcano

    Science.gov (United States)

    Dehn, Jonathan; Dean, Kenneson; Engle, Kevin; Izbekov, Pavel

    2002-07-01

    Shishaldin Volcano, Unimak Island Alaska, began showing signs of thermal unrest in satellite images on 9 February 1999. A thermal anomaly and small steam plume were detected at the summit of the volcano in short-wave thermal infrared AVHRR (advanced very high resolution radiometer) satellite data. This was followed by over 2 months of changes in the observed thermal character of the volcano. Initially, the thermal anomaly was only visible when the satellite passed nearly directly over the volcano, suggesting a hot source deep in the central crater obscured from more oblique satellite passes. The "zenith angle" needed to see the anomaly increased with time, presumably as the thermal source rose within the conduit. Based on this change, an ascent rate of ca. 14 m per day for the thermal source was estimated, until it reached the summit on around 21 March. It is thought that Strombolian activity began around this time. The precursory activity culminated in a sub-Plinian eruption on 19 April, ejecting ash to over 45,000 ft. (13,700 m). The thermal energy output through the precursory period was calculated based on geometric constraints unique to Shishaldin. These calculations show fluctuations that can be tied to changes in the eruptive character inferred from seismic records and later geologic studies. The remote location of this volcano made satellite images a necessary observation tool for this eruption. To date, this is the longest thermal precursory activity preceding a sub-Plinian eruption recorded by satellite images in the region. This type of thermal monitoring of remote volcanoes is central in the efforts of the Alaska Volcano Observatory to provide timely warnings of volcanic eruption, and mitigate their associated hazards to air-traffic and local residents.

  5. Digital Data for Volcano Hazards in the Mount Jefferson Region, Oregon

    Science.gov (United States)

    Schilling, S.P.; Doelger, S.; Walder, J.S.; Gardner, C.A.; Conrey, R.M.; Fisher, B.J.

    2008-01-01

    Mount Jefferson has erupted repeatedly for hundreds of thousands of years, with its last eruptive episode during the last major glaciation which culminated about 15,000 years ago. Geologic evidence shows that Mount Jefferson is capable of large explosive eruptions. The largest such eruption occurred between 35,000 and 100,000 years ago. If Mount Jefferson erupts again, areas close to the eruptive vent will be severely affected, and even areas tens of kilometers (tens of miles) downstream along river valleys or hundreds of kilometers (hundreds of miles) downwind may be at risk. Numerous small volcanoes occupy the area between Mount Jefferson and Mount Hood to the north, and between Mount Jefferson and the Three Sisters region to the south. These small volcanoes tend not to pose the far-reaching hazards associated with Mount Jefferson, but are nonetheless locally important. A concern at Mount Jefferson, but not at the smaller volcanoes, is the possibility that small-to-moderate sized landslides could occur even during periods of no volcanic activity. Such landslides may transform as they move into lahars (watery flows of rock, mud, and debris) that can inundate areas far downstream. The geographic information system (GIS) volcano hazard data layer used to produce the Mount Jefferson volcano hazard map in USGS Open-File Report 99-24 (Walder and others, 1999) is included in this data set. Both proximal and distal hazard zones were delineated by scientists at the Cascades Volcano Observatory and depict various volcano hazard areas around the mountain.

  6. New insights into Kilauea's volcano dynamics brought by large-scale relative relocation of microearthquakes

    Science.gov (United States)

    Got, J.-L.; Okubo, P.

    2003-01-01

    We investigated the microseismicity recorded in an active volcano to infer information concerning the volcano structure and long-term dynamics, by using relative relocations and focal mechanisms of microearthquakes. There were 32,000 earthquakes of the Mauna Loa and Kilauea volcanoes recorded by more than eight stations of the Hawaiian Volcano Observatory seismic network between 1988 and 1999. We studied 17,000 of these events and relocated more than 70%, with an accuracy ranging from 10 to 500 m. About 75% of these relocated events are located in the vicinity of subhorizontal decollement planes, at a depth of 8-11 km. However, the striking features revealed by these relocation results are steep southeast dipping fault planes working as reverse faults, clearly located below the decollement plane and which intersect it. If this decollement plane coincides with the pre-Mauna Loa seafloor, as hypothesized by numerous authors, such reverse faults rupture the pre-Mauna Loa oceanic crust. The weight of the volcano and pressure in the magma storage system are possible causes of these ruptures, fully compatible with the local stress tensor computed by Gillard et al. [1996]. Reverse faults are suspected of producing scarps revealed by kilometer-long horizontal slip-perpendicular lineations along the decollement surface and therefore large-scale roughness, asperities, and normal stress variations. These are capable of generating stick-slip, large-magnitude earthquakes, the spatial microseismic pattern observed in the south flank of Kilauea volcano, and Hilina-type instabilities. Rupture intersecting the decollement surface, causing its large-scale roughness, may be an important parameter controlling the growth of Hawaiian volcanoes.

  7. Preliminary volcano-hazard assessment for Augustine Volcano, Alaska

    Science.gov (United States)

    Waythomas, Christopher F.; Waitt, Richard B.

    1998-01-01

    Augustine Volcano is a 1250-meter high stratovolcano in southwestern Cook Inlet about 280 kilometers southwest of Anchorage and within about 300 kilometers of more than half of the population of Alaska. Explosive eruptions have occurred six times since the early 1800s (1812, 1883, 1935, 1964-65, 1976, and 1986). The 1976 and 1986 eruptions began with an initial series of vent-clearing explosions and high vertical plumes of volcanic ash followed by pyroclastic flows, surges, and lahars on the volcano flanks. Unlike some prehistoric eruptions, a summit edifice collapse and debris avalanche did not occur in 1812, 1935, 1964-65, 1976, or 1986. However, early in the 1883 eruption, a portion of the volcano summit broke loose forming a debris avalanche that flowed to the sea. The avalanche initiated a small tsunami reported on the Kenai Peninsula at English Bay, 90 kilometers east of the volcano. Plumes of volcanic ash are a major hazard to jet aircraft using Anchorage International and other local airports. Ashfall from future eruptions could disrupt oil and gas operations and shipping activities in Cook Inlet. Eruptions similar to the historical and prehistoric eruptions are likely in Augustine's future.

  8. Workshops on Volcanoes at Santiaguito (Guatemala): A community effort to inform and highlight the outstanding science opportunities at an exceptional laboratory volcano

    Science.gov (United States)

    Johnson, J. B.; Escobar-Wolf, R. P.; Pineda, A.

    2016-12-01

    Santiaguito is one of Earth's most reliable volcanic spectacles and affords opportunity to investigate dome volcanism, including hourly explosions, pyroclastic flows, block lava flows, and sporadic paroxysmal eruptions. The cubic km dome, active since 1922, comprises four coalescing structures. Lava effusion and explosions are ideally observed from a birds-eye perspective at the summit of Santa Maria volcano (1200 m above and 2700 km from the active Caliente vent). Santiaguito is also unstable and dangerous. Thousands of people in farms and local communities are exposed to hazards from frequent lahars, pyroclastic flows, and potentially large sector-style dome collapses. In January 2016 more than 60 volcano scientists, students, postdocs, and observatory professionals traveled to Santiaguito to participate in field study and discussion about the science and hazards of Santiaguito. The event facilitated pre- and syn-workshop field experiments, including deployment of seismic, deformation, infrasound, multi-spectral gas and thermal sensing, UAV reconnaissance, photogrammetry, and petrologic and rheologic sampling. More than 55 participants spent the night on the 3770-m summit of Santa Maria to partake in field observations. The majority of participants also visited lahar and pyroclastic flow-impacted regions south of the volcano. A goal of the workshop was to demonstrate how multi-disciplinary observations are critical to elucidate volcano eruption dynamics. Integration of geophysical and geochemical observation, and open exchange of technological advances, is vital to achieve the next generation of volcano discovery. Toward this end data collected during the workshop are openly shared within the broader volcanological community. Another objective of the workshop was to bring attention to an especially hazardous and little-studied volcanic system. The majority of workshop attendees had not visited the region and their participation was hoped to seed future

  9. Dual-central-wavelength passively mode-locked diffusion-bonded Nd:YVO4/Nd:GdVO4 laser with a semiconductor saturable absorber mirror

    Science.gov (United States)

    Chang, F. L.; Sung, C. L.; Huang, T. L.; Wu, T. W.; Cho, H. H.; Liang, H. C.; Chen, Y. F.

    2017-08-01

    A dual-central-wavelength passively mode-locked laser with full modulation in the 0.31 THz optical beating is achieved by using a diffusion-bonded Nd:YVO4/Nd:GdVO4 crystal and a semiconductor saturable absorber mirror. The output power of the dual-band emission is well balanced by tuning the focal position of the pump waist. At a pump power of 13 W, the total output power is up to 2.7 W with a repetition rate of 297.9 MHz. The autocorrelation traces clearly reveal the synchronization of the dual-band emission. Moreover, an analytical model is developed to manifest the multi-pulse structure caused by the etalon effect of the gain medium. More important, we experimentally verify that the etalon effect can be completely eliminated by using the wedge-cut diffusion-bonded Nd:YVO4/Nd:GdVO4 crystal.

  10. Comparative study of passively Q-switched c-cut Nd:YVO4/Nd:YAG lasers based on CVD graphene and controlled operation

    Science.gov (United States)

    Jia, Fuqiang; Liu, Pei; Li, Kang; Chen, Hao; Cheng, Yongjie; Cai, Zhiping; Copner, Nigel

    2017-07-01

    In this paper, a comparative study of passively Q-switched c-cut Nd:YVO4 and Nd:YAG lasers using four different layers CVD graphene as saturable absorber are demonstrated experimentally for the first time. Moreover, it is successful to accurately control the frequency of repetition rates of the CVD graphern passively Q-switched lasers by pulsed pump. The impacts of laser materials, layers of CVD graphene and cavity length on output parameters are investigated intensively as well, the result shows that the c-cut Nd:YVO4 is a promising laser media compared with Nd:YAG for passively Q-switched lasers based on CVD graphene, as it has better performances in pulse width, pulse energy and peak power. A useful and cost-effective way to generate stable pulsed lasers by CVD graphene or other novel saturable materials are demonstrated.

  11. Power scaling of Nd:YVO4 and Nd:GdVO4 disk lasers using synthetic diamond as a heat spreader.

    Science.gov (United States)

    Millar, P; Kemp, A J; Burns, D

    2009-03-15

    A newly developed low-birefringence synthetic diamond is shown to be an effective intracavity heat spreader in Nd:YVO4 and Nd:GdVO4 disk lasers. A cw output power of 25.7 W from only one double pass of the pump is reported. The diamond heat spreader is shown to increase the pump power density at which fracture occurs.

  12. Modulated Pulse Generations in a Laser-diode-pumped Passively Q-switched Intracavity-frequency-doubling Nd∶YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    郑加安; 赵圣之; 陈磊

    2002-01-01

    The investigative results of modulated pulse output from an LD end-pumped passively Q-switched intracavity-frequency-doubling Nd∶YVO4/KTP laser with Cr4+∶YAG saturable absorber are presented. The numerical stimulations of these modulated pulses are carried out basing on the rate equations. It indicated that the modulations are attribute to the frequency beating of two eigenstates of the resonant polarized modes. The theoretical calculations are in good agreement with the experimental observations.

  13. A Bidirectional, Diode-Pumped, Passively Mode-Locked Nd:YVO4 Ring Laser with a Low-Temperature-Grown Semiconductor Saturable Absorber Mirror

    Institute of Scientific and Technical Information of China (English)

    CAI Zhi-Qiang; YAO Jian-Quan; WANG Peng; WANG Yong-Gang; ZHANG Zhi-Gang

    2007-01-01

    We report the operation of a bidirectional picosecond pulsed ring Nd:YVO4 laser based on a low-temperaturegrown semiconductor saturable absorber mirror. Except for the laser crystal, the six-mirror ring laser cavity has no intra-cavity elements such as focusing lens or mirror. The bidirectional mode locked pluses are obtained at the repetition rate of 117.5MHz, pulse duration of Sips, power of 2×200 mW.

  14. Building a Subduction Zone Observatory

    Science.gov (United States)

    Gomberg, Joan S.; Bodin, Paul; Bourgeois, Jody; Cashman, Susan; Cowan, Darrel; Creager, Kenneth C.; Crowell, Brendan; Duvall, Alison; Frankel, Arthur; Gonzalez, Frank; Houston, Heidi; Johnson, Paul; Kelsey, Harvey; Miller, Una; Roland, Emily C.; Schmidt, David; Staisch, Lydia; Vidale, John; Wilcock, William; Wirth, Erin

    2016-01-01

    Subduction zones contain many of Earth’s most remarkable geologic structures, from the deepest oceanic trenches to glacier-covered mountains and steaming volcanoes. These environments formed through spectacular events: Nature’s largest earthquakes, tsunamis, and volcanic eruptions are born here.

  15. The Farid & Moussa Raphael Observatory

    Science.gov (United States)

    Hajjar, R.

    2017-06-01

    The Farid & Moussa Raphael Observatory (FMRO) at Notre Dame University Louaize (NDU) is a teaching, research, and outreach facility located at the main campus of the university. It located very close to the Lebanese coast, in an urbanized area. It features a 60-cm Planewave CDK telescope, and instruments that allow for photometric and spetroscopic studies. The observatory currently has one thinned, back-illuminated CCD camera, used as the main imager along with Johnson-Cousin and Sloan photometric filters. It also features two spectrographs, one of which is a fiber fed echelle spectrograph. These are used with a dedicated CCD. The observatory has served for student projects, and summer schools for advanced undergraduate and graduate students. It is also made available for use by the regional and international community. The control system is currently being configured for remote observations. A number of long-term research projects are also being launched at the observatory.

  16. Deep Space Climate Observatory (DSCOVR)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Deep Space Climate ObserVatoRy (DSCOVR) satellite is a NOAA operated asset located at the first Lagrange point (L1). This places it approximately 1% of the...

  17. Geomagnetic Observatory Database February 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) maintains an active database of worldwide geomagnetic observatory...

  18. Islamic Astronomical Instruments and Observatories

    Science.gov (United States)

    Heidarzadeh, Tofigh

    This chapter is a brief survey of astronomical instruments being used and developed in Islamic territories from the eighth to the fifteenth centuries as well as a concise account of major observatories and observational programs in this period.

  19. Mount Rainier, a decade volcano

    Energy Technology Data Exchange (ETDEWEB)

    Kuehn, S.C.; Hooper, P.R. (Washington State Univ., Pullman, WA (United States). Dept. of Geology); Eggers, A.E. (Univ. of Puget Sound, Tacoma, WA (United States). Dept. of Geology)

    1993-04-01

    Mount Rainier, recently designated as a decade volcano, is a 14,410 foot landmark which towers over the heavily populated southern Puget Sound Lowland of Washington State. It last erupted in the mid-1800's and is an obvious threat to this area, yet Rainier has received little detailed study. Previous work has divided Rainier into two distinct pre-glacial eruptive episodes and one post-glacial eruptive episode. In a pilot project, the authors analyzed 253 well-located samples from the volcano for 27 major and trace elements. Their objective is to test the value of chemical compositions as a tool in mapping the stratigraphy and understanding the eruptive history of the volcano which they regard as prerequisite to determining the petrogenesis and potential hazard of the volcano. The preliminary data demonstrates that variation between flows is significantly greater than intra-flow variation -- a necessary condition for stratigraphic use. Numerous flows or groups of flows can be distinguished chemically. It is also apparent from the small variation in Zr abundances and considerable variation in such ratios as Ba/Nb that fractional crystallization plays a subordinate role to some form of mixing process in the origin of the Mount Rainier lavas.

  20. Standardisation of the USGS Volcano Alert Level System (VALS): analysis and ramifications

    Science.gov (United States)

    Fearnley, C. J.; McGuire, W. J.; Davies, G.; Twigg, J.

    2012-11-01

    The standardisation of volcano early warning systems (VEWS) and volcano alert level systems (VALS) is becoming increasingly common at both the national and international level, most notably following UN endorsement of the development of globally comprehensive early warning systems. Yet, the impact on its effectiveness, of standardising an early warning system (EWS), in particular for volcanic hazards, remains largely unknown and little studied. This paper examines this and related issues through evaluation of the emergence and implementation, in 2006, of a standardised United States Geological Survey (USGS) VALS. Under this upper-management directive, all locally developed alert level systems or practices at individual volcano observatories were replaced with a common standard. Research conducted at five USGS-managed volcano observatories in Alaska, Cascades, Hawaii, Long Valley and Yellowstone explores the benefits and limitations this standardisation has brought to each observatory. The study concludes (1) that the process of standardisation was predominantly triggered and shaped by social, political, and economic factors, rather than in response to scientific needs specific to each volcanic region; and (2) that standardisation is difficult to implement for three main reasons: first, the diversity and uncertain nature of volcanic hazards at different temporal and spatial scales require specific VEWS to be developed to address this and to accommodate associated stakeholder needs. Second, the plural social contexts within which each VALS is embedded present challenges in relation to its applicability and responsiveness to local knowledge and context. Third, the contingencies of local institutional dynamics may hamper the ability of a standardised VALS to effectively communicate a warning. Notwithstanding these caveats, the concept of VALS standardisation clearly has continuing support. As a consequence, rather than advocating further commonality of a standardised

  1. Effect of Nd3+ concentration on CW and pulsed performance of fiber-coupled diode laser pumped Nd:YVO4 laser at 1064 nm

    Indian Academy of Sciences (India)

    Pranab K Mukhopadhyay; K Ranganathan; Jogy George; S K Sharma; T P S Nathan

    2002-07-01

    The effect of Nd3+ concentration on the CW and Q-switched laser performances at 1064 nm from Nd : YVO4 has been studied under diode laser pumping in identical laser configuration. The Nd3+ concentrations used were 1, 2 and 3 at. % in YVO4 crystals. Under the CW operations we have compared the thermal lensing effect, slope efficiencies and also the beam quality at the fourth-order degeneracy configuration. Q-switching was done with the help of an acousto-optic modulator and we have compared the pulses obtained from Nd : YVO4 laser with different doping concentration. It was found that the 1 at.%-doped crystal is the best, offering highest optical-to-optical conversion efficiency (55%), lowest fractional heat load (24%), highest pulse energy (80 J) and shortest pulse width (20 ns). It was also found that there was not much difference in performances for 2 and 3 at. %-doped crystals both in CW and Q-switched configurations.

  2. Forecasting eruptions using pre-eruptive seismic patterns at Sinabung Volcano, Indonesia

    Science.gov (United States)

    McCausland, W. A.; White, R. A.; Hendrasto, M.; Gunawan, H.; Indrastuti, N.; Triastuti, H.; Suparman, Y.; Putra, A.

    2015-12-01

    Forecasting the size, timing and style of volcanic eruptions is of primary interest to observatories and civil authorities world-wide, yet most observatories only have access to long-term data at a very limited number of volcanoes under their jurisdiction. When extensive long-term data sets are available to responsible agencies, volcanic eruptive size, timing and style can usually be successfully forecast using current monitoring data and knowledge of precursory eruptive patterns, enabling the communication of timely forecasts to civil authorities. Experienced agencies, such as Indonesia's Center for Volcanology and Geologic Hazards Mitigation and the USAID-USGS Volcano Disaster Assistance Program, utilize extensive collective experiences with multiple monitoring streams over multiple eruption cycles and across volcano types to successfully forecast eruption size, style and onset, as well as changes in eruptive style and size within ongoing eruptions. The longest-term real-time monitoring parameter commonly available at volcanoes worldwide is seismic data. Seismic data is a direct measure of rate-dependent strain changes in the magmatic system from the deep magmatic input to shallow eruptive processes. Patterns of pre-eruptive earthquakes coupled with other available monitoring data and conceptual models of magma ascent enable short-term forecasting of eruption size, style, and onset. First order event locations, characterization of background seismicity, and changes in earthquake types and energy release are most important to successful eruption forecasting. This study demonstrates how this approach has been used to successfully forecast eruption onsets, changes in eruptive style, and to change alert levels and extend or contract evacuation zones during the ongoing eruption of Sinabung Volcano, Indonesia.

  3. Two 18th Century Observatories of Ireland

    Science.gov (United States)

    Hambleton, Robert

    A visit to the two major observatories of Ireland, Armagh Observatory in Northern Ireland, and Dunsink Observatory in Dublin. Mentioned are Herschel, Thomas Grubb, Thomas Jones transit instrument, Howard Grubb, Kew Observatory, John Arnold & Sons clocks, Birr Castle, and the Earl of Rosse.

  4. The Carl Sagan solar and stellar observatories as remote observatories

    Science.gov (United States)

    Saucedo-Morales, J.; Loera-Gonzalez, P.

    In this work we summarize recent efforts made by the University of Sonora, with the goal of expanding the capability for remote operation of the Carl Sagan Solar and Stellar Observatories, as well as the first steps that have been taken in order to achieve autonomous robotic operation in the near future. The solar observatory was established in 2007 on the university campus by our late colleague A. Sánchez-Ibarra. It consists of four solar telescopes mounted on a single equatorial mount. On the other hand, the stellar observatory, which saw the first light on 16 February 2010, is located 21 km away from Hermosillo, Sonora at the site of the School of Agriculture of the University of Sonora. Both observatories can now be remotely controlled, and to some extent are able to operate autonomously. In this paper we discuss how this has been accomplished in terms of the use of software as well as the instruments under control. We also briefly discuss the main scientific and educational objectives, the future plans to improve the control software and to construct an autonomous observatory on a mountain site, as well as the opportunities for collaborations.

  5. The Calibration System of the HAWC Gamma-Ray Observatory

    CERN Document Server

    Solares, Hugo A Ayala; Hui, C Michelle; Lauer, Robert J; Ren, Zhixiang; Greus, Francisco Salesa; Zhou, Hao

    2015-01-01

    The HAWC collaboration has recently completed the construction of a gamma-ray observatory at an altitude of 4100 meters on the slope of the Sierra Negra volcano in the state of Puebla, Mexico. In order to achieve an optimal angular resolution, energy reconstruction, and cosmic-ray background suppression for the air showers observed by HAWC, it is crucial to obtain good timing and charge calibrations of the photosensors in the detector. The HAWC calibration is based on a laser system which is able to deliver short light pulses to all the tanks in the array. The light intensity can range over 7 orders of magnitude, broad enough to cover all the dynamic range of the PMT readout electronics. In this contribution we will present the HAWC calibration system, together with the methods used to calibrate the detector.

  6. Synthesis of YVO4∶Eu Fluorescent Nanomaterials and Their Applications in Development of Latent Fingerprints%YVO4∶Eu纳米荧光材料的合成及其在手印显现中的应用

    Institute of Scientific and Technical Information of China (English)

    王猛

    2015-01-01

    以聚乙烯亚胺(PEI)为修饰剂,采用水热法合成了荧光强度较高、颗粒粒径较小的YVO4∶Eu纳米荧光材料,并讨论了合成该纳米荧光材料的反应机理。通过透射电子显微镜(T EM )、X射线衍射(XRD )、红外光谱(FTIR)、荧光光谱(FS)对纳米荧光材料的粒径形貌、晶体结构、表面官能团、荧光性能进行表征,该纳米荧光材料的粒径尺度约为30 nm、形貌为单分散的球形、晶体结构为四方YVO4晶型、其表面为PEI修饰,在254 nm紫外光的激发下能够发射出较强的红色荧光。将合成的YVO4∶Eu纳米荧光材料应用于常见光滑客体表面汗潜手印的粉末法显现中,并考详细察了手印显现灵敏度、抗背景颜色干扰能力等因素的影响。实验结果显示,经过YVO4∶Eu纳米荧光材料显现的手印在254 nm紫外灯照射下能够发射出明亮的红色荧光,手印纹线清晰连贯、细节特征明显、对比反差强烈、背景干扰较小。与传统的荧光粉末显现法相比,该显现方法具有较高的显现灵敏度和较低的背景干扰。%YVO4 ∶Eu fluorescent nanomaterials with small size and strong fluorescent intensity were synthesized via a hydro‐thermal method by using polyethylenimine (PEI) as the modifier ,and the reaction mechanism of this synthesis was also dis‐cussed .The as‐synthesized nanomaterials were characterized through transmission electron microscopy (TEM ) ,X‐ray diffrac‐tion (XRD) measurements ,Fourier transform infrared (FT‐IR) spectroscopy and fluorescence spectroscopy (FS) .The as‐pre‐pared fluorescent nanomaterials were well‐dispersed and spherical in shape with an average diameter of about 30 nm ,which were modified with a layer of PEI on surfaces .The fluorescent nanomaterials were of pure tetragonal YVO4 structure .They could emit strong red fluorescence under the 254 nm ultraviolet excitation .The YVO4 ∶Eu fluorescent dry

  7. Near-Infrared Luminescence Enhancement by Co-Doped Bi3+ in YVO4∶Yb3+%Bi3+掺杂对YVO4∶Yb3+近红外发光的敏化作用

    Institute of Scientific and Technical Information of China (English)

    肖全兰; 孟建新; 谢丽娟; 张蕤

    2011-01-01

    用高温固相法合成了Yb3+、Bi3+共掺的YVO4,研究了BI3+的掺入对YVO4∶Yb3+发光光谱的影响和近红外发光的敏化作用.X射线衍射图谱研究表明:掺入Yb3+、Bi3+之后,基质YVO4的品格结构没有发生明显变化.Bi3+的掺入不仅显著增强了样品中yb3+的特征远红外发光强度,还使YVO4∶Yb3+激发光谱的范围红移,当Bi3+掺入的摩尔分数从0增加到0.05时,样品的最强激发峰位置从335 nm红移至352 nm,激发光谱范围由300-360 nm扩宽至300-430 nm.优化的Bi3+掺入量为0.03.初步讨论了VO3-4,Bi3+和Yb3+间的能量传递机理.结果表明Bi3+的共掺使YVO4∶Yb3+样品对长波紫外光的响应性能大大改善,作为一种基于量子剪裁的光谱转换材料,可以更好地匹配太阳光的能量谱,有助于提高硅太阳能电池的光电转换效率.%The near-infrared (NIR) luminescence phosphor Yb3+,Bi3+ co-doped YVO4 was prepared by a conventional solid state method and the sensitization of Yb3+ near-infrared luminescence by Bi3+ was investigated. By co-doping with Bi3+ from 0 to 0.05 the characteristic NIR luminescence of Yb3+ in the YVO4 matrix was greatly enhanced and the strongest site of the excitation wavelength red-shifted from 335 to 352 nm while the wavelength range of the excitation spectrum broadened from 300-360 to 300-430 nm. The optimized Bi3+ content is 0.03. The possible energy transfer mechanism among VO3- 4, Bi3+, and Yb3+ was discussed. We conclude that the NIR luminescence of YVO4:Yb3+ can be remarkably improved by co-doping with Bi3+ and its absorbance matches better with the solar energy spectrum. YVO4:Yb3+, Bi3+ is a promising spectral converter for silicon solar cells and it is expected to improve the photoelectric conversion efficiency.

  8. Contiuous gas monitoring at the volcano Galeras, Colombia

    Science.gov (United States)

    Faber, E.; Morán, C.; Poggenburg, J.; Garzón, G.; Teschner, M.; Weinlich, F. H.

    2003-04-01

    (1) Federal Institute for Geosciences and Natural Resources, Hannover, Germany (e.faber@bgr.de), (2) Instituto de Investigación en Geocientifica, Mineroambiental y Nuclear - INGEOMINAS, San Juan de Pasto, Colombia (3) Instituto de Investigación en Geocientifica, Mineroambiental y Nuclear - INGEOMINAS, Manizales, Colombia A gas monitoring system has been installed on the volcano Galeras in Colombia as part of a multi-parameter station. Gases are extracted from the fumarolic vapour through a short pipe. After the water has been condensed the gas passes over sensors for carbon dioxide, sulphur dioxide and radon. Other parameters measured are temperature of the fumarolic vapour, fumarolic pressure, temperature of the ambient air and the ambient atmospheric pressure. The signals of the sensors are digitised in the electronics. The digital data are transmitted every 6 seconds by a telemetry system to the observatory down in the city of Pasto via a repeater station at the rim of the Galeras. The system at the volcano is powered by batteries connected to solar panels. Data are stored in the observatory, they are plotted and compared with all the other information of the multi-parameter station. Although the various compounds of the gas system are well preserved for the very aggressive environment close to the fumarole some problems still remain: Sulphur often plugs the pipe to the sensors and requires maintenance more often than desired. As the volcano is most of the time in clouds the installed solar power system (about 400 Watts maximum power) does not enable to run the system at the fumarole (consumption about 15 Watts) continuously during all nights. Despite these still existing problems some results have been obtained encouraging us to continue the operation of the system, to further develop the technical quality and to increase the number of fumaroles included into a growing monitoring network. In March 2000 seismic activity in the crater increased accompanied by a

  9. GEOSCOPE Observatory Recent Developments

    Science.gov (United States)

    Leroy, N.; Pardo, C.; Bonaime, S.; Stutzmann, E.; Maggi, A.

    2010-12-01

    The GEOSCOPE observatory consists of a global seismic network and a data center. The 31 GEOSCOPE stations are installed in 19 countries, across all continents and on islands throughout the oceans. They are equipped with three component very broadband seismometers (STS1 or STS2) and 24 or 26 bit digitizers, as required by the Federation of Seismic Digital Network (FDSN). In most stations, a pressure gauge and a thermometer are also installed. Currently, 23 stations send data in real or near real time to GEOSCOPE Data Center and tsunami warning centers. In 2009, two stations (SSB and PPTF) have been equipped with warpless base plates. Analysis of one year of data shows that the new installation decreases long period noise (20s to 1000s) by 10 db on horizontal components. SSB is now rated in the top ten long period stations for horizontal components according to the LDEO criteria. In 2010, Stations COYC, PEL and RER have been upgraded with Q330HR, Metrozet electronics and warpless base plates. They have been calibrated with the calibration table CT-EW1 and the software jSeisCal and Calex-EW. Aluminum jars are now installed instead of glass bells. A vacuum of 100 mbars is applied in the jars which improves thermal insulation of the seismometers and reduces moisture and long-term corrosion in the sensor. A new station RODM has just been installed in Rodrigues Island in Mauritius with standard Geoscope STS2 setup: STS2 seismometer on a granite base plate and covered by cooking pot and thermal insulation, it is connected to Q330HR digitizer, active lightning protection, Seiscomp PC and real-time internet connection. Continuous data of all stations are collected in real time or with a delay by the GEOSCOPE Data Center in Paris where they are validated, archived and made available to the international scientific community. Data are freely available to users by different interfaces according data types (see : http://geoscope.ipgp.fr) - Continuous data in real time coming

  10. Volcano monitoring using the Global Positioning System: Filtering strategies

    Science.gov (United States)

    Larson, K.M.; Cervelli, Peter; Lisowski, M.; Miklius, Asta; Segall, P.; Owen, S.

    2001-01-01

    Permanent Global Positioning System (GPS) networks are routinely used for producing improved orbits and monitoring secular tectonic deformation. For these applications, data are transferred to an analysis center each day and routinely processed in 24-hour segments. To use GPS for monitoring volcanic events, which may last only a few hours, real-time or near real-time data processing and subdaily position estimates are valuable. Strategies have been researched for obtaining station coordinates every 15 min using a Kalman filter; these strategies have been tested on data collected by a GPS network on Kilauea Volcano. Data from this network are tracked continuously, recorded every 30 s, and telemetered hourly to the Hawaiian Volcano Observatory. A white noise model is heavily impacted by data outages and poor satellite geometry, but a properly constrained random walk model fits the data well. Using a borehole tiltmeter at Kilauea's summit as ground-truth, solutions using different random walk constraints were compared. This study indicates that signals on the order of 5 mm/h are resolvable using a random walk standard deviation of 0.45 cm/???h. Values lower than this suppress small signals, and values greater than this have significantly higher noise at periods of 1-6 hours. Copyright 2001 by the American Geophysical Union.

  11. Volcano monitoring using the Global Positioning System: Filtering strategies

    Science.gov (United States)

    Larson, Kristine M.; Cervelli, Peter; Lisowski, Michael; Miklius, Asta; Segall, Paul; Owen, Susan

    2001-09-01

    Permanent Global Positioning System (GPS) networks are routinely used for producing improved orbits and monitoring secular tectonic deformation. For these applications, data are transferred to an analysis center each day and routinely processed in 24-hour segments. To use GPS for monitoring volcanic events, which may last only a few hours, real-time or near real-time data processing and subdaily position estimates are valuable. Strategies have been researched for obtaining station coordinates every 15 min using a Kalman filter; these strategies have been tested on data collected by a GPS network on Kilauea Volcano. Data from this network are tracked continuously, recorded every 30 s, and telemetered hourly to the Hawaiian Volcano Observatory. A white noise model is heavily impacted by data outages and poor satellite geometry, but a properly constrained random walk model fits the data well. Using a borehole tiltmeter at Kilauea's summit as ground-truth, solutions using different random walk constraints were compared. This study indicates that signals on the order of 5 mm/h are resolvable using a random walk standard deviation of 0.45 cm/√h. Values lower than this suppress small signals, and values greater than this have significantly higher noise at periods of 1-6 hours.

  12. Observatory Bibliographies as Research Tools

    Science.gov (United States)

    Rots, Arnold H.; Winkelman, S. L.

    2013-01-01

    Traditionally, observatory bibliographies were maintained to provide insight in how successful a observatory is as measured by its prominence in the (refereed) literature. When we set up the bibliographic database for the Chandra X-ray Observatory (http://cxc.harvard.edu/cgi-gen/cda/bibliography) as part of the Chandra Data Archive ((http://cxc.harvard.edu/cda/), very early in the mission, our objective was to make it primarily a useful tool for our user community. To achieve this we are: (1) casting a very wide net in collecting Chandra-related publications; (2) including for each literature reference in the database a wealth of metadata that is useful for the users; and (3) providing specific links between the articles and the datasets in the archive that they use. As a result our users are able to browse the literature and the data archive simultaneously. As an added bonus, the rich metadata content and data links have also allowed us to assemble more meaningful statistics about the scientific efficacy of the observatory. In all this we collaborate closely with the Astrophysics Data System (ADS). Among the plans for future enhancement are the inclusion of press releases and the Chandra image gallery, linking with ADS semantic searching tools, full-text metadata mining, and linking with other observatories' bibliographies. This work is supported by NASA contract NAS8-03060 (CXC) and depends critically on the services provided by the ADS.

  13. Aleutian Islands Coastal Resources Inventory and Environmental Sensitivity Maps: VOLCANOS (Volcano Points)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains point locations of active volcanoes as compiled by Motyka et al., 1993. Eighty-nine volcanoes with eruptive phases in the Quaternary are...

  14. Digital Data for Volcano Hazards of the Three Sisters Region, Oregon

    Science.gov (United States)

    Schilling, S.P.; Doelger, S.; Scott, W.E.; Iverson, R.M.

    2008-01-01

    Three Sisters is one of three active volcanic centers that lie close to rapidly growing communities and resort areas in Central Oregon. The major composite volcanoes of this area are clustered near the center of the region and include South Sister, Middle Sister, and Broken Top. Additionally, hundreds of mafic volcanoes are scattered throughout the Three Sisters area. These range from small cinder cones to large shield volcanoes like North Sister and Belknap Crater. Hazardous events include landslides from the steep flanks of large volcanoes and floods, which need not be triggered by eruptions, as well as eruption-triggered events such as fallout of tephra (volcanic ash) and lava flows. A proximal hazard zone roughly 20 kilometers (12 miles) in diameter surrounding the Three Sisters and Broken Top could be affected within minutes of the onset of an eruption or large landslide. Distal hazard zones that follow river valleys downstream from the Three Sisters and Broken Top could be inundated by lahars (rapid flows of water-laden rock and mud) generated either by melting of snow and ice during eruptions or by large landslides. Slow-moving lava flows could issue from new mafic volcanoes almost anywhere within the region. Fallout of tephra from eruption clouds can affect areas hundreds of kilometers (miles) downwind, so eruptions at volcanoes elsewhere in the Cascade Range also contribute to volcano hazards in Central Oregon. Scientists at the Cascades Volcano Observatory created a geographic information system (GIS) data set which depicts proximal and distal lahar hazard zones as well as a regional lava flow hazard zone for Three Sisters (USGS Open-File Report 99-437, Scott and others, 1999). The various distal lahar zones were constructed from LaharZ software using 20, 100, and 500 million cubic meter input flow volumes. Additionally, scientists used the depositional history of past events in the Three Sisters Region as well as experience and judgment derived from the

  15. Results from the Autonomous Triggering of in situ Sensors on Kilauea Volcano, HI, from Eruption Detection by Spacecraft

    Science.gov (United States)

    Doubleday, J.; Behar, A.; Davies, A.; Mora-Vargas, A.; Tran, D.; Abtahi, A.; Pieri, D. C.; Boudreau, K.; Cecava, J.

    2008-12-01

    Response time in acquiring sensor data in volcanic emergencies can be greatly improved through use of autonomous systems. For instance, ground-based observations and data processing applications of the JPL Volcano Sensor Web have promptly triggered spacecraft observations [e.g., 1]. The reverse command and information flow path can also be useful, using autonomous analysis of spacecraft data to trigger in situ sensors. In this demonstration project, SO2 sensors were incorporated into expendable "Volcano Monitor" capsules and placed downwind of the Pu'u 'O'o vent of Kilauea volcano, Hawai'i. In nominal (low) power conservation mode, data from these sensors were collected and transmitted every hour to the Volcano Sensor Web through the Iridium Satellite Network. When SO2 readings exceeded a predetermined threshold, the modem within the Volcano Monitor sent an alert to the Sensor Web, and triggered a request for prompt Earth Observing-1 (EO-1) spacecraft data acquisition. The Volcano Monitors were also triggered by the Sensor Web in response to an eruption detection by the MODIS instrument on Terra. During these pre- defined "critical events" the Sensor Web ordered the SO2 sensors within the Volcano Monitor to increase their sampling frequency to every 5 minutes (high power "burst mode"). Autonomous control of the sensors' sampling frequency enabled the Sensor Web to monitor and respond to rapidly evolving conditions, and allowed rapid compilation and dissemination of these data to the scientific community. Reference: [1] Davies et al., (2006) Eos, 87, (1), 1 and 5. This work was performed at the Jet Propulsion Laboratory-California Institute of Technology, under contract to NASA. Support was provided by the NASA AIST program, the Idaho Space Grant Consortium, and the New Mexico Space Grant Program. We also especially thank the personnel of the USGS Hawaiian Volcano Observatory for their invaluable scientific guidance and logistical assistance.

  16. Digital Data for Volcano Hazards from Mount Rainier, Washington, Revised 1998

    Science.gov (United States)

    Schilling, S.P.; Doelger, S.; Hoblitt, R.P.; Walder, J.S.; Driedger, C.L.; Scott, K.M.; Pringle, P.T.; Vallance, J.W.

    2008-01-01

    Mount Rainier at 4393 meters (14,410 feet) is the highest peak in the Cascade Range; a dormant volcano having glacier ice that exceeds that of any other mountain in the conterminous United States. This tremendous mass of rock and ice, in combination with great topographic relief, poses a variety of geologic hazards, both during inevitable future eruptions and during the intervening periods of repose. The volcano's past behavior is the best guide to possible future hazards. The written history (about A.D. 1820) of Mount Rainier includes one or two small eruptions, several small debris avalanches, and many small lahars (debris flows originating on a volcano). In addition, prehistoric deposits record the types, magnitudes, and frequencies of other events, and areas that were affected. Mount Rainier deposits produced since the latest ice age (approximately during the past 10,000 years) are well preserved. Studies of these deposits indicate we should anticipate potential hazards in the future. Some phenomena only occur during eruptions such as tephra falls, pyroclastic flows and surges, ballistic projectiles, and lava flows while others may occur without eruptive activity such as debris avalanches, lahars, and floods. The five geographic information system (GIS) volcano hazard data layers used to produce the Mount Rainier volcano hazard map in USGS Open-File Report 98-428 (Hoblitt and others, 1998) are included in this data set. Case 1, case 2, and case 3 layers were delineated by scientists at the Cascades Volcano Observatory and depict various lahar innundation zones around the mountain. Two additional layers delineate areas that may be affected by post-lahar sedimentation (postlahar layer) and pyroclastic flows (pyroclastic layer).

  17. Modeling eruptions of Karymsky volcano

    OpenAIRE

    Ozerov, A.; Ispolatov, I.; Lees, J.

    2001-01-01

    A model is proposed to explain temporal patterns of activity in a class of periodically exploding Strombolian-type volcanos. These patterns include major events (explosions) which follow each other every 10-30 minutes and subsequent tremor with a typical period of 1 second. This two-periodic activity is thought to be caused by two distinct mechanisms of accumulation of the elastic energy in the moving magma column: compressibility of the magma in the lower conduit and viscoelastic response of...

  18. Automated tracking of lava lake level using thermal images at Kīlauea Volcano, Hawai’i

    Science.gov (United States)

    Patrick, Matthew R.; Swanson, Don; Orr, Tim

    2016-01-01

    Tracking the level of the lava lake in Halema‘uma‘u Crater, at the summit of Kīlauea Volcano, Hawai’i, is an essential part of monitoring the ongoing eruption and forecasting potentially hazardous changes in activity. We describe a simple automated image processing routine that analyzes continuously-acquired thermal images of the lava lake and measures lava level. The method uses three image segmentation approaches, based on edge detection, short-term change analysis, and composite temperature thresholding, to identify and track the lake margin in the images. These relative measurements from the images are periodically calibrated with laser rangefinder measurements to produce real-time estimates of lake elevation. Continuous, automated tracking of the lava level has been an important tool used by the U.S. Geological Survey’s Hawaiian Volcano Observatory since 2012 in real-time operational monitoring of the volcano and its hazard potential.

  19. Australian network of magnetic observatories

    Science.gov (United States)

    Barton, C. E.

    Six magnetic observatories are presently operated by the Australian Bureau of Mineral Resources, Geology and Geophysics (BMR), with assistance from various other organizations. Variometer recordings are made of three or more elements of the field at minute intervals, and absolute measurements are made weekly. There are four observatories on the continent (Canberra, Gnangara, Charters Towers, and Learmonth), one on Macquarie Island, and one at Mawson Station in eastern Antarctica (Figure 1). In addition, semiweekly absolute observations of the field (D, H, and F) are made at the other two permanent Australian Antarctic bases (Casey and Davis). A three-axis fluxgate magnetometer (EDA Electronics, Toronto , Canada) is operated independently by the Upper Atmosphere Physics group at Davis. Monthly mean values, K indices, and information about magnetic disturbances are published monthly in the BMR Geophysical Observatory Report.

  20. Theory in a Virtual Observatory

    CERN Document Server

    Teuben, P; Hut, P; Levy, S; Makino, J; McMillan, S; Zwart, S P; Slavin, S D; Teuben, Peter; Young, Dave De; Hut, Piet; Levy, Stuart; Makino, Jun; Millan, Steve Mc; Zwart, Simon Portegies; Slavin, Shawn

    2001-01-01

    During the last couple of years, observers have started to make plans for a Virtual Observatory, as a federation of existing data bases, connected through levels of software that enable rapid searches, correlations, and various forms of data mining. We propose to extend the notion of a Virtual Observatory by adding archives of simulations, together with interactive query and visualization capabilities, as well as ways to simulate observations of simulations in order to compare them with observations. For this purpose, we have already organized two small workshops, earlier in 2001, in Tucson and Aspen. We have also provided concrete examples of theory data, designed to be federated with a Virtual Observatory. These data stem from a project to construct an archive for our large-scale simulations using the GRAPE-6 (a 32-Teraflops special purpose computer for stellar dynamics). We are constructing interfaces by which remote observers can observe these simulations. In addition, these data will enable detailed comp...

  1. Mexican Virtual Solar Observatory project

    Science.gov (United States)

    Santillán, Alfredo J.; Hernández, Liliana; Salas, Guillermo; Sánchez, Antonio; González, Alejandro; Franco, José

    2007-08-01

    The Virtual Solar Observatory (VSO) concept outlines a software environment for searching, obtaining and analyzing data from archives of solar data that are distributed at many different observatories around the world (Hill 2006, in this volume). The VSO, however, not only provides fast and reliable access to the existing data of Solar Active Regions, but also represents a powerful and unique tool to perform numerical simulations of the evolution and present state of solar phenomena. Two centers at UNAM, the Institute of Astronomy (IA) and the Supercomputer Center (DGSCA), along with the Sonora University, are working together to create the Mexican Virtual Solar Observatory (MVSO) that will be part of a wider national effort.

  2. Integrating SAR with Optical and Thermal Remote Sensing for Operational Near Real-Time Volcano Monitoring

    Science.gov (United States)

    Meyer, F. J.; Webley, P.; Dehn, J.; Arko, S. A.; McAlpin, D. B.

    2013-12-01

    Volcanic eruptions are among the most significant hazards to human society, capable of triggering natural disasters on regional to global scales. In the last decade, remote sensing techniques have become established in operational forecasting, monitoring, and managing of volcanic hazards. Monitoring organizations, like the Alaska Volcano Observatory (AVO), are nowadays heavily relying on remote sensing data from a variety of optical and thermal sensors to provide time-critical hazard information. Despite the high utilization of these remote sensing data to detect and monitor volcanic eruptions, the presence of clouds and a dependence on solar illumination often limit their impact on decision making processes. Synthetic Aperture Radar (SAR) systems are widely believed to be superior to optical sensors in operational monitoring situations, due to the weather and illumination independence of their observations and the sensitivity of SAR to surface changes and deformation. Despite these benefits, the contributions of SAR to operational volcano monitoring have been limited in the past due to (1) high SAR data costs, (2) traditionally long data processing times, and (3) the low temporal sampling frequencies inherent to most SAR systems. In this study, we present improved data access, data processing, and data integration techniques that mitigate some of the above mentioned limitations and allow, for the first time, a meaningful integration of SAR into operational volcano monitoring systems. We will introduce a new database interface that was developed in cooperation with the Alaska Satellite Facility (ASF) and allows for rapid and seamless data access to all of ASF's SAR data holdings. We will also present processing techniques that improve the temporal frequency with which hazard-related products can be produced. These techniques take advantage of modern signal processing technology as well as new radiometric normalization schemes, both enabling the combination of

  3. Earthquakes - Volcanoes (Causes and Forecast)

    Science.gov (United States)

    Tsiapas, E.

    2009-04-01

    EARTHQUAKES - VOLCANOES (CAUSES AND FORECAST) ELIAS TSIAPAS RESEARCHER NEA STYRA, EVIA,GREECE TEL.0302224041057 tsiapas@hol.gr The earthquakes are caused by large quantities of liquids (e.g. H2O, H2S, SO2, ect.) moving through lithosphere and pyrosphere (MOHO discontinuity) till they meet projections (mountains negative projections or projections coming from sinking lithosphere). The liquids are moved from West Eastward carried away by the pyrosphere because of differential speed of rotation of the pyrosphere by the lithosphere. With starting point an earthquake which was noticed at an area and from statistical studies, we know when, where and what rate an earthquake may be, which earthquake is caused by the same quantity of liquids, at the next east region. The forecast of an earthquake ceases to be valid if these components meet a crack in the lithosphere (e.g. limits of lithosphere plates) or a volcano crater. In this case the liquids come out into the atmosphere by the form of gasses carrying small quantities of lava with them (volcano explosion).

  4. Environmental Observatories and Hydrologic Modeling

    Science.gov (United States)

    Hooper, R. P.; Duncan, J. M.

    2006-12-01

    During the past several years, the environmental sciences community has been attempting to design large- scale obsevatories that will transform the science. A watershed-based observatory has emerged as an effective landscape unit for a broad range of environmental sciences and engineering. For an effective observatory, modeling is a central requirement because models are precise statements of the hypothesized conceptual organization of watersheds and of the processes believed to be controlling hydrology of the watershed. Furthermore, models can serve to determine the value of existing data and the incremental value of any additional data to be collected. Given limited resources, such valuation is mandatory for an objective design of an observatory. Modeling is one part of a "digital watershed" that must be constructed for any observatory, a concept that has been developed by the CUAHSI Hydrologic Information Systems project. A digital watershed has three functions. First, it permits assembly of time series (such as stream discharge or precipitation measurements), static spatial coverages (such as topography), and dynamic fields (such as precipitation radar and other remotely sensed data). Second, based upon this common data description, a digital observatory permits multiple conceptualizations of the observatory to be created and to be stored. These conceptualizations could range from lumped box-and-arrow watershed models, to semi-distributed topographically based models, to three-dimensional finite element models. Finally, each conceptualization can lead to multiple models--that is, a set of equations that quantitatively describe hydrologic (or biogeochemical or geomorphologic) processes through libraries of tools that can be linked as workflow sequences. The advances in cyberinfrastructure that allow the storage of multiple conceptualizations and multiple model formulations of these conceptualizations promise to accelerate advances in environmental science both

  5. Active Deformation of Etna Volcano Combing IFSAR and GPS data

    Science.gov (United States)

    Lundgren, Paul

    1997-01-01

    The surface deformation of an active volcano is an important indicator of its eruptive state and its hazard potential. Mount Etna volcano in Sicily is a very active volcano with well documented eruption episodes.

  6. Astronomical Research Using Virtual Observatories

    Directory of Open Access Journals (Sweden)

    M Tanaka

    2010-01-01

    Full Text Available The Virtual Observatory (VO for Astronomy is a framework that empowers astronomical research by providing standard methods to find, access, and utilize astronomical data archives distributed around the world. VO projects in the world have been strenuously developing VO software tools and/or portal systems. Interoperability among VO projects has been achieved with the VO standard protocols defined by the International Virtual Observatory Alliance (IVOA. As a result, VO technologies are now used in obtaining astronomical research results from a huge amount of data. We describe typical examples of astronomical research enabled by the astronomical VO, and describe how the VO technologies are used in the research.

  7. Campgrounds in Hawaii Volcanoes National Park

    Data.gov (United States)

    National Park Service, Department of the Interior — This dataset provides campground locations in Hawaii Volcanoes National Park. Information about facilities, water availability, permit requirements and type of...

  8. Three-dimensional velocity structure of the Galeras volcano (Colombia) from passive local earthquake tomography

    Science.gov (United States)

    Vargas, Carlos Alberto; Torres, Roberto

    2015-08-01

    A three-dimensional estimation of the Vp, Vs and Vp/Vs ratio structure at Galeras volcano was conducted by means of passive local earthquake tomography. 14,150 volcano-tectonic events recorded by 58 stations in the seismological network established for monitoring the volcanic activity by the Colombian Geological Survey - Pasto Volcano Observatory between the years 1989 and 2015, were inverted by using the LOTOS code. The seismic events are associated with shear-stress fractures in solid rock as a response to pressure induced by magma flow. Tomography resolution tests suggest a depth of imaging that yield 10 km from the summit of the main crater, illuminating a large portion of the volcanic structure and the interaction of tectonic features like the Buesaco and Silvia-Pijao faults. Full catalog tomographic inversion, that represents the stacked image of the volcanic structure or the most permanent features underneath the volcano, shows vertical structures aligned with seismicity beneath the main crater. We hypothesize that these structures correspond to a system of ducts or fractures through which magma and fluid phases flow up from deeper levels toward the top and related with the intersection of the surface traces of the Silvia-Pijao and Buesaco faults.

  9. Nd:YVO4 laser removal of graffiti from granite. Influence of paint and rock properties on cleaning efficacy

    Science.gov (United States)

    Rivas, T.; Pozo, S.; Fiorucci, M. P.; López, A. J.; Ramil, A.

    2012-12-01

    This paper presents the cleaning efficiency results for four differently coloured graffiti paints applied to two types of granitic stone by Nd:YVO4 laser at 355 nm. The paints were characterized in terms of mineralogy and chemistry using x-ray fluorescence, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM); paint absorbance in the ultraviolet-visible-infrared range (200-2000 nm) was also assessed. The studied granites had different mineralogy, texture and porosity properties. Cleaning efficiency was evaluated by polarized microscopy, SEM, FTIR spectroscopy and spectrophotometer colour measurements. The results indicate differences in the effectiveness of surface cleaning for the blue, red and black paints as opposed to the silver paint, mainly attributed to chemical composition. No evidence was found that the granite properties had a bearing on laser effectiveness, although the degree, type and spatial distribution of transgranular fissures in the stone affected the overall assessment of cleaning effectiveness. Polarized light microscopy observations and colour measurements showed that the intensity and distribution of fissures affect the depth of paint penetration, ultimately affecting the cleaning efficiency for both granites.

  10. Broadband supercontinuum generation in a telecommunication fibre pumped by a nanosecond Tm, Ho:YVO{sub 4} laser

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Ren-Lai; Ren Jian-Cun; Lou Shu-Li [Department of control engineering, Naval Aeronautical and Astronautical University, Yantai 264001 (China); Ju You-Lun; Wang Yue-Zhu [National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2015-07-31

    Broadband supercontinuum (SC) generation in a telecommunication fibre [8/125-μm single mode fibre (SMF) and 50/125-μm multimode fibre (MMF)] directly pumped by a nanosecond Q-switched Tm, Ho:YVO{sub 4} laser is demonstrated. At a 7-kHz pulse repetition frequency (PRF), an output average power of 0.53 W in the 1.95 – 2.5-μm spectral band and 3.51 W in the 1.9 – 2.6-μm spectral band are achieved in SMF and MMF, respectively (the corresponding optic-to-optic conversion efficiencies are 34.6% and 73.7%). The output spectra have extremely high flat segments in the range 2070 – 2390 nm and 2070 – 2475 nm with negligible intensity variation (less than 2%). The SC average power is scalable from 2.1 to 4.2 W by increasing the PRF from 5 to 15 kHz, while maintaining pump power. Compared with the input pump pulse, the output SC pulse width is broadened, and no split is found. The stability of the output SC power has been monitored for a week and the fluctuations being less than 6%. (control of radiation parameters)

  11. Effect of substrate temperature on structure and luminescence properties of YVO4:Eu3+ thin films grown by PLD

    Science.gov (United States)

    Foka, K. E.; Dejene, B. F.; Swart, H. C.

    2016-03-01

    YVO4:Eu3+ thin films were deposited by pulse laser deposition at substrate temperatures of 200, 300 and 400 °C. The oxygen deposition background pressure was also changed from 20 to 85 mTorr at a substrate temperature of 400 °C. The films deposited at the higher temperatures showed a tetragonal phase in consistent with the standard JCPDS card 17-0341. The X-ray diffraction patterns obtained from the 200 °C sample showed only a very small peak at the (200) orientation. The other phosphor thin film showed an improved crystalline structure when the temperature was increased. Scanning electron microscope images indicated larger particles on the surface at the higher temperatures. Atomic force microscopy results showed smooth surfaces with small particles at lower temperatures and an increase in surface roughness at higher temperatures due to the improvement in crystallinity. The photoluminescence showed the typical emission peaks of Eu3+ in the red region at 594 and 618 nm attributed to the 5D0-7F1 and 5D0-7F2 transitions. The peaks at 652 and 699 nm corresponding to the 5D0-7F3 and 5D0-7F4 transitions were also observed. The spectra showed an increase in PL intensity when the deposition temperature and oxygen pressure were increased.

  12. Virtual Investigations of an Active Deep Sea Volcano

    Science.gov (United States)

    Sautter, L.; Taylor, M. M.; Fundis, A.; Kelley, D. S.; Elend, M.

    2013-12-01

    Axial Seamount, located on the Juan de Fuca spreading ridge 300 miles off the Oregon coast, is an active volcano whose summit caldera lies 1500 m beneath the sea surface. Ongoing construction of the Regional Scale Nodes (RSN) cabled observatory by the University of Washington (funded by the NSF Ocean Observatories Initiative) has allowed for exploration of recent lava flows and active hydrothermal vents using HD video mounted on the ROVs, ROPOS and JASON II. College level oceanography/marine geology online laboratory exercises referred to as Online Concept Modules (OCMs) have been created using video and video frame-captured mosaics to promote skill development for characterizing and quantifying deep sea environments. Students proceed at their own pace through a sequence of short movies with which they (a) gain background knowledge, (b) learn skills to identify and classify features or biota within a targeted environment, (c) practice these skills, and (d) use their knowledge and skills to make interpretations regarding the environment. Part (d) serves as the necessary assessment component of the laboratory exercise. Two Axial Seamount-focused OCMs will be presented: 1) Lava Flow Characterization: Identifying a Suitable Cable Route, and 2) Assessing Hydrothermal Vent Communities: Comparisons Among Multiple Sulfide Chimneys.

  13. Efficient diode stack end-pumped continuous-wave Nd∶YVO4 slab lasers%激光二极管端面抽运Nd:YVO4晶体连续输出板条激光器研究

    Institute of Scientific and Technical Information of China (English)

    张恒利; 闫莹; 杜克明

    2008-01-01

    报道了利用激光二极管列阵端面抽运Nd:YVO4混合腔板条激光器连续波输出的实验结果,获得近衍射极限的60 W连续激光输出.实验证明两种晶体输出功率相当,低掺杂浓度的Nd:YVO4晶体更有利于得到近衍射极限的高功率输出,但同时对冷却水温度的变化也较敏感.

  14. Research on Methods for Building Volcano Disaster Information System--taking Changbai Mountain as an example

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xuexia; BO Liqun; LU Xingchang

    2001-01-01

    Volcano eruption is one of the most serious geological disasters in the world. There are volcanoes in every territory on the earth, about a thousand in China, among which Changbai Mountain Volcano, Wudalianchi Volcano and Tengchong Volcano are the most latent catastrophic eruptive active volcanoes. The paper, following an instance of Changbai Mountain Volcano, expounds that monitoring, forecasting and estimating volcano disaster by building Volcano Disaster Information System (VDIS) is feasible to alleviate volcano disaster.

  15. Multidisciplinary development of Belerofont Observatory.

    Science.gov (United States)

    Babović, V.

    1997-08-01

    Belerofont Astronomical Observatory in Kragujevac, inaugurated on the occasion of the appearance of Halley's comet on February 26, 1986, develops astronomical activities among pupils, university youth and people interested in cosmic phenomena. In preparing a course of astronomy and astrophysics in the physics study curriculum, the society tends toward a multidisciplinary way of work.

  16. The National Ecological Observatory Network

    Science.gov (United States)

    Michener, W. K.

    2006-05-01

    The National Ecological Observatory Network (NEON) is a research platform designed to advance understanding of how ecosystems and organisms respond to variations in climate and changes in land use. NEON is the first long-term ecological observatory conceived as a continental-scale network; equipped with standardized sensors, cyberinfrastructure, and data-collection protocols across the network; and designed to simultaneously address a common set of research questions and support investigator-driven ecological research in all regions of the United States. The Observatory focuses on variations in climate and land use because they are primary drivers of the Nation's environmental challenges, as identified by the National Research Council--i.e., biodiversity, biogeochemical cycles, climate change, hydroecology, infectious disease, invasive species, and land use. At the broadest scale, NEON links the complexity of climate variation to the behavior of ecological systems, a core aspect of ecological complexity. At the same time, because of the complexity of the interactions among humans and ecosystems, the network design includes NEON sites in wild, managed and urban systems within climate domains. Observatory data will also be part of a national education program designed to advance ecological science literacy through new programs and activities that develop and promote scientific ways of thinking.

  17. Seafloor Observatory Science: a Review

    Directory of Open Access Journals (Sweden)

    L. Beranzoli

    2006-06-01

    Full Text Available The ocean exerts a pervasive influence on Earth’s environment. It is therefore important that we learn how this system operates (NRC, 1998b; 1999. For example, the ocean is an important regulator of climate change (e.g., IPCC, 1995. Understanding the link between natural and anthropogenic climate change and ocean circulation is essential for predicting the magnitude and impact of future changes in Earth’s climate. Understanding the ocean, and the complex physical, biological, chemical, and geological systems operating within it, should be an important goal for the opening decades of the 21st century. Another fundamental reason for increasing our understanding of ocean systems is that the global economy is highly dependent on the ocean (e.g., for tourism, fisheries, hydrocarbons, and mineral resources (Summerhayes, 1996. The establishment of a global network of seafloor observatories will help to provide the means to accomplish this goal. These observatories will have power and communication capabilities and will provide support for spatially distributed sensing systems and mobile platforms. Sensors and instruments will potentially collect data from above the air-sea interface to below the seafloor. Seafloor observatories will also be a powerful complement to satellite measurement systems by providing the ability to collect vertically distributed measurements within the water column for use with the spatial measurements acquired by satellites while also providing the capability to calibrate remotely sensed satellite measurements (NRC, 2000. Ocean observatory science has already had major successes. For example the TAO array has enabled the detection, understanding and prediction of El Niño events (e.g., Fujimoto et al., 2003. This paper is a world-wide review of the new emerging “Seafloor Observatory Science”, and describes both the scientific motivations for seafloor observatories and the technical solutions applied to their architecture. A

  18. Volcanic hazards at Atitlan volcano, Guatemala

    Science.gov (United States)

    Haapala, J.M.; Escobar Wolf, R.; Vallance, James W.; Rose, William I.; Griswold, J.P.; Schilling, S.P.; Ewert, J.W.; Mota, M.

    2006-01-01

    Atitlan Volcano is in the Guatemalan Highlands, along a west-northwest trending chain of volcanoes parallel to the mid-American trench. The volcano perches on the southern rim of the Atitlan caldera, which contains Lake Atitlan. Since the major caldera-forming eruption 85 thousand years ago (ka), three stratovolcanoes--San Pedro, Toliman, and Atitlan--have formed in and around the caldera. Atitlan is the youngest and most active of the three volcanoes. Atitlan Volcano is a composite volcano, with a steep-sided, symmetrical cone comprising alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs. Eruptions of Atitlan began more than 10 ka [1] and, since the arrival of the Spanish in the mid-1400's, eruptions have occurred in six eruptive clusters (1469, 1505, 1579, 1663, 1717, 1826-1856). Owing to its distance from population centers and the limited written record from 200 to 500 years ago, only an incomplete sample of the volcano's behavior is documented prior to the 1800's. The geologic record provides a more complete sample of the volcano's behavior since the 19th century. Geologic and historical data suggest that the intensity and pattern of activity at Atitlan Volcano is similar to that of Fuego Volcano, 44 km to the east, where active eruptions have been observed throughout the historical period. Because of Atitlan's moderately explosive nature and frequency of eruptions, there is a need for local and regional hazard planning and mitigation efforts. Tourism has flourished in the area; economic pressure has pushed agricultural activity higher up the slopes of Atitlan and closer to the source of possible future volcanic activity. This report summarizes the hazards posed by Atitlan Volcano in the event of renewed activity but does not imply that an eruption is imminent. However, the recognition of potential activity will facilitate hazard and emergency preparedness.

  19. 2003 Eruption of Chikurachki Volcano, Paramushir Island, Northern Kuriles, Russia

    Science.gov (United States)

    Schneider, D. J.; Girina, O. A.; Neal, C. A.; Kotenko, L.; Terentiev, N. S.; Izbekov, P.; Belousov, I.; Senyukov, S.; Ovsyannikov, A. A.

    2003-12-01

    Chikurachki Volcano in the northern Kurile Islands erupted for the second time in two years in mid-April 2003. Although the Kamchatka Volcanic Eruptions Response Team (KVERT) received word of a possible eruption from residents of Paramushir Island on April 17, poor weather precluded confirmation of volcanic activity, and the exact start date is uncertain. On April 18, during routine satellite image analysis, the Alaska Volcano Observatory (AVO) detected an ash cloud from Chikurachki in GMS data and immediately notified the Federal Aviation Administration (FAA), National Weather Service, and other agencies. Subsequent formal alerts were issued through aviation and meteorological channels as outlined in the Alaska Interagency Operating Plan for Volcanic Ash Episodes. Thermal infrared imagery and trajectory models suggested the initial cloud was relatively low-level (below 25,000 ft ASL), however this height was not well constrained. Over the next several months, activity at Chikurachki consisted largely of strombolian bursts producing intermittent ash clouds reaching heights of generally less than 10-13,000 ft. ASL. Ash fall was noted as far as 60 km downwind. The last confirmed eruptive activity was June 16, 2003. During the eruption, AVHRR, MODIS, and GMS satellites captured images of the ash cloud as far as 300 km generally east and southeast of the volcano in the region heavily traveled North Pacific air routes. The propagation of volcanic clouds was monitored using visual and infrared channels and included a routine split-window analysis. Weak thermal anomalies were detected in AVHRR images suggesting minimal effusive activity near the central vent. Over the course of the eruption, aviation and meteorological authorities in Russia, the U.S., and Japan issued official notices regarding the eruption and the position and estimated height of the ash plume. Impacts to aviation were minor due to the low-level and intermittent nature of the eruption. Chikurachki is a

  20. Augustine Volcano, Cook Inlet, Alaska (January 31, 2006)

    Science.gov (United States)

    2006-01-01

    Since last spring, the U.S. Geological Survey's Alaska Volcano Observatory (AVO) has detected increasing volcanic unrest at Augustine Volcano in Cook Inlet, Alaska near Anchorage. Based on all available monitoring data, AVO regards that an eruption similar to 1976 and 1986 is the most probable outcome. During January, activity has been episodic, and characterized by emission of steam and ash plumes, rising to altitudes in excess of 9,000 m (30,000 ft), and posing hazards to aircraft in the vicinity. In the last week, volcanic flows have been seen on the volcano's flanks. An ASTER thermal image was acquired at night at 22:50 AST on January 31, 2006, during an eruptive phase of Augustine. The image shows three volcanic flows down the north flank of Augustine as white (hot) areas. The eruption plume spreads out to the east in a cone shape: it appears dark blue over the summit because it is cold and water ice dominates the composition; further downwind a change to orange color indicates that the plume is thinning and the signal is dominated by the presence of ash. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance. The U.S. science team is located at NASA's Jet Propulsion

  1. Norwegian Ocean Observatory Network (NOON)

    Science.gov (United States)

    Ferré, Bénédicte; Mienert, Jürgen; Winther, Svein; Hageberg, Anne; Rune Godoe, Olav; Partners, Noon

    2010-05-01

    The Norwegian Ocean Observatory Network (NOON) is led by the University of Tromsø and collaborates with the Universities of Oslo and Bergen, UniResearch, Institute of Marine Research, Christian Michelsen Research and SINTEF. It is supported by the Research Council of Norway and oil and gas (O&G) industries like Statoil to develop science, technology and new educational programs. Main topics relate to ocean climate and environment as well as marine resources offshore Norway from the northern North Atlantic to the Arctic Ocean. NOON's vision is to bring Norway to the international forefront in using cable based ocean observatory technology for marine science and management, by establishing an infrastructure that enables real-time and long term monitoring of processes and interactions between hydrosphere, geosphere and biosphere. This activity is in concert with the EU funded European Strategy Forum on Research Infrastructures (ESFRI) roadmap and European Multidisciplinary Seafloor Observation (EMSO) project to attract international leading research developments. NOON envisions developing towards a European Research Infrastructure Consortium (ERIC). Beside, the research community in Norway already possesses a considerable marine infrastructure that can expand towards an international focus for real-time multidisciplinary observations in times of rapid climate change. PIC The presently established cable-based fjord observatory, followed by the establishment of a cable-based ocean observatory network towards the Arctic from an O&G installation, will provide invaluable knowledge and experience necessary to make a successful larger cable-based observatory network at the Norwegian and Arctic margin (figure 1). Access to large quantities of real-time observation from the deep sea, including high definition video, could be used to provide the public and future recruits to science a fascinating insight into an almost unexplored part of the Earth beyond the Arctic Circle

  2. The Old Vilnius University Observatory (in German)

    Science.gov (United States)

    Matulaitytė, S.

    The history of the Vilnius University Astronomical Observatory in 1753--1882 is described (in German). The observatory is one of the oldest astronomical institutions in Europe. In 2003 its 250th anniversary was celebrated.

  3. VEPP Exercise: Volcanic Activity and Monitoring of Pu`u `O`o, Kilauea Volcano, Hawaii

    Science.gov (United States)

    Rodriguez, L. A.

    2010-12-01

    participate in a 1-hr discussion and will report on what they think will happen at Kilauea in the near future. Students will be evaluated based on group participation, progress reports and discussions, the written and oral reports, and the final wrap-up exercise. This project can be modified to be based on any 10-week period in the eruption, for which data can be accessed through the VEPP web site. It can also include data from other volcanoes, if data are available from volcano observatories and/or government agencies.

  4. Predictability of Volcano Eruption: lessons from a basaltic effusive volcano

    CERN Document Server

    Grasso, J R

    2003-01-01

    Volcano eruption forecast remains a challenging and controversial problem despite the fact that data from volcano monitoring significantly increased in quantity and quality during the last decades.This study uses pattern recognition techniques to quantify the predictability of the 15 Piton de la Fournaise (PdlF) eruptions in the 1988-2001 period using increase of the daily seismicity rate as a precursor. Lead time of this prediction is a few days to weeks. Using the daily seismicity rate, we formulate a simple prediction rule, use it for retrospective prediction of the 15 eruptions,and test the prediction quality with error diagrams. The best prediction performance corresponds to averaging the daily seismicity rate over 5 days and issuing a prediction alarm for 5 days. 65% of the eruptions are predicted for an alarm duration less than 20% of the time considered. Even though this result is concomitant of a large number of false alarms, it is obtained with a crude counting of daily events that are available fro...

  5. Newberry Volcano's youngest lava flows

    Science.gov (United States)

    Robinson, Joel E.; Donnelly-Nolan, Julie M.; Jensen, Robert A.

    2015-01-01

    Most of Newberry Volcano's youngest lava flows are found within the Newberry National Volcanic Monument in central Oregon. Established November 5, 1990, the monument is managed by the U.S. Forest Service as part of the Deschutes National Forest. Since 2011, a series of aerial surveys over the monument collected elevation data using lidar (light detection and ranging) technology, which uses lasers to directly measure the ground surface. These data record previously unseen detail in the volcano’s numerous lava flows and vents. On average, a laser return was collected from the ground’s surface every 2.17 feet (ft) with ±1.3 inches vertical precision.

  6. Observatory bibliographies: a vital resource in operating an observatory

    Science.gov (United States)

    Winkelman, Sherry; Rots, Arnold

    2016-07-01

    The Chandra Data Archive (CDA) maintains an extensive observatory bibliography. By linking the published articles with the individual datasets analyzed in the paper, we have the opportunity to join the bibliographic metadata (including keywords, subjects, objects, data references from other observatories, etc.) with the meta- data associated with the observational datasets. This rich body of information is ripe for far more sophisticated data mining than the two repositories (publications and data) would afford individually. Throughout the course of the mission the CDA has investigated numerous questions regarding the impact of specific types of Chandra programs such as the relative science impact of GTO, GO, and DDT programs or observing, archive, and theory programs. Most recently the Chandra bibliography was used to assess the impact of programs based on the size of the program to examine whether the dividing line between standard and large projects should be changed and whether another round of X-ray Visionary Programs should be offered. Traditionally we have grouped observations by proposal when assessing the impact of programs. For this investigation we aggregated observations by pointing and instrument configuration such that objects observed multiple times in the mission were considered single observing programs. This change in perspective has given us new ideas for assessing the science impact of Chandra and for presenting data to our users. In this paper we present the methodologies used in the recent study, some of its results, and most importantly some unexpected insights into assessing the science impact of an observatory.

  7. Near-diffraction-limited,35.4 W laser-diode end-pumped Nd:YVO4 slab laser operating at 1342 nm.

    Science.gov (United States)

    Yan, Ying; Zhang, Hengli; Liu, Yang; Yu, Xilong; Zhang, Huaijin; He, Jingliang; Xin, Jianguo

    2009-07-15

    A diode stack end-pumped Nd:YVO4 slab laser at 1342 nm with near-diffraction-limited beam quality by using a hybrid resonator was presented. At a pump power of 139.5 W, laser power of 35.4 W was obtained with a conversion efficiency of 25.4% of the laser diode to laser output. The beam quality M2 factors were measured to be 1.2 in the unstable direction and 1.3 in the stable direction at the output power of 29 W.

  8. Diode-pumped, Cr:YAG passively Q-switched and mode-locked Nd:YVO4/KTP green laser

    Institute of Scientific and Technical Information of China (English)

    Junying Wang(王军营); Quan Zheng(郑权); Qinghua Xue(薛庆华); Huiming Tan(檀慧明)

    2003-01-01

    The phenomena of simultaneous Q-switching and mode-locking in a diode-pumped Nd:YVO4/Cr:YAG/KTP green laser are reported and discussed in this paper. With 5.3-W pump power, by using a nearlyhemispherical cavity (the cavity length is only 97 mm), the results of modulation depth of 70% and theperiod of 0.6 ns are obtained, the output power and the repetitive frequency of Q-switched pulse are 90mW and 12 kHz, respectively.

  9. High power 888 nm optical fiber end-pumped Nd:YVO4 picosecond regenerative amplifier at hundreds kHz

    Science.gov (United States)

    Bai, Zhenao; Fan, Zhongwei; Lian, Fuqiang; Tan, Tan; Bai, Zhenxu; Yang, Chao; Kang, Zhijun; Liu, Chang

    2016-10-01

    This paper describes a demonstration of a high power 888 nm end-pumped Nd:YVO4 picosecond regenerative amplifier operated at high repetition rate. By utilizing an all-fiber mode-locking picosecond laser as seed source and 888 nm continuous wave (CW) as pumping source, we obtained regenerative amplified output at 1064.07 nm with spectrum width 0.16 nm, pulse width of 38 ps, maximum power of 21 W, and the repetition rate is continuously adjustable from 300 to 500 kHz. The regenerative amplifier has high power stability and high compact structure.

  10. Parametric optimization of Nd-YVO4 laser for straight scribing on silver nanowire based conductive thin films by Taguchi method

    Science.gov (United States)

    Chuang, Ho-Chiao; Lee, Wen-Fu

    2014-04-01

    This study presents parameter optimization of laser scribing on silver nanowire based conductive thin films and a high-precision Nd-YVO4 (wavelength, 532 nm) laser is used to perform scribing experiments to replace the traditional wet etching process. The laser beam is directly focused on conductive thin films and vaporizes the silver nanowire which is coated on the thin film; consequently it is a non-polluting processes. The main objective of this study is to perform laser scribing experiments to cut off the silver nanowire on the thin film without damaging the flexible PET (Polyethylene terephthalate) substrate.

  11. Mode-locking of a high power, 888 nm pumped Nd:YVO4 laser using nonlinear polarization rotation via Type I second harmonic generation.

    Science.gov (United States)

    Schäfer, Christoph; Fries, Christian; Theobald, Christian; L'huillier, Johannes A

    2013-01-15

    Continuous-wave mode-locking of a laser exploiting the nonlinear polarization rotation (NPR) technique via Type I second harmonic generation is demonstrated for the first time. The NPR is generated by a lithium triborate crystal and transformed into nonlinear cavity losses of a 888 nm pumped Nd:YVO4 laser. Self-starting, reliable mode-locking has been achieved at a high average output power of 20.6 W and a pulse duration of 7.3 ps. Furthermore, transform limited pulses down to 2.7 ps have been demonstrated at 9.9 W.

  12. The MicroObservatory Net

    Science.gov (United States)

    Brecher, K.; Sadler, P.

    1994-12-01

    A group of scientists, engineers and educators based at the Harvard-Smithsonian Center for Astrophysics (CfA) has developed a prototype of a small, inexpensive and fully integrated automated astronomical telescope and image processing system. The project team is now building five second generation instruments. The MicroObservatory has been designed to be used for classroom instruction by teachers as well as for original scientific research projects by students. Probably in no other area of frontier science is it possible for a broad spectrum of students (not just the gifted) to have access to state-of-the-art technologies that would allow for original research. The MicroObservatory combines the imaging power of a cooled CCD, with a self contained and weatherized reflecting optical telescope and mount. A microcomputer points the telescope and processes the captured images. The MicroObservatory has also been designed to be used as a valuable new capture and display device for real time astronomical imaging in planetariums and science museums. When the new instruments are completed in the next few months, they will be tried with high school students and teachers, as well as with museum groups. We are now planning to make the MicroObservatories available to students, teachers and other individual users over the Internet. We plan to allow the telescope to be controlled in real time or in batch mode, from a Macintosh or PC compatible computer. In the real-time mode, we hope to give individual access to all of the telescope control functions without the need for an "on-site" operator. Users would sign up for a specific period of time. In the batch mode, users would submit jobs for the telescope. After the MicroObservatory completed a specific job, the images would be e-mailed back to the user. At present, we are interested in gaining answers to the following questions: (1) What are the best approaches to scheduling real-time observations? (2) What criteria should be used

  13. The Pierre Auger Cosmic Ray Observatory

    NARCIS (Netherlands)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Al Samarai, I.; Albert, J. N.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muniz, J.; Batista, R. Alves; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Aramo, C.; Aranda, V. M.; Argiro, S.; Arisaka, K.; Arneodo, F.; Arqueros, F.; Asch, T.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Awal, N.; Badescu, A. M.; Balzer, M.; Barber, K. B.; Barbosa, A.; Barenthien, N.; Barkhausen, M.; Baeuml, J.; Baus, C.; Beatty, J.; Becker, K. H.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bergmann, T.; Bertaina, M. E.; Biermann, P. L.; Bilhaut, R.; Billoir, P.; Blaes, S. G.; Blanco, M.; Bleve, C.; Bluemer, H.; Bohacova, M.; Bolz, H.; Boncioli, D.; Bonifaz, C.; Bonino, R.; Boratav, M.; Borodai, N.; Bracci, F.; Brack, J.; Brancus, I.; Bridgeman, A.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Camin, D.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Castera, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chiosso, M.; Chudoba, J.; Cilmo, M.; Clark, P. D. J.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Coleman, A.; Collica, L.; Colombo, E.; Colonges, S.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cooper, M. J.; Coppens, J.; Cordier, A.; Courty, B.; Coutu, S.; Covault, C. E.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; de Vries, K. D.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Diaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, C.; Dolron, P.; Dorofeev, A.; Hasankiadeh, Q. Dorosti; Dova, M. T.; D'Urso, D.; Ebr, J.; Engel, R.; Epele, L. N.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fernandes, M.; Ferrero, A.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipcic, A.; Fox, B. D.; Fraenkel, E. D.; Fratu, O.; Freire, M. M.; Froehlich, U.; Fuchs, B.; Fulgione, W.; Fujii, T.; Garcia, B.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gate, F.; Geenen, H.; Gemmeke, H.; Genolini, B.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Gibbs, K.; Giller, M.; Giudice, N.; Glaser, C.; Glass, H.; Gomez Berisso, M.; Gomez Vitale, P. F.; Goncalves, P.; Gonzalez, J. G.; Gonzalez, N.; Gookin, B.; Gora, D.; Gordon, J.; Gorgi, A.; Gorham, P.; Gotink, W.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Grygar, J.; Guardone, N.; Guarino, F.; Guedes, G. P.; Guglielmi, L.; Habraken, R.; Hampel, M. R.; Hansen, P.; Harari, D.; Harmsma, S.; Harrison, T. A.; Hartmann, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hoerandel, J. R.; Horneffer, A.; Horvat, M.; Horvath, P.; Hrabovsky, M.; Huber, D.; Hucker, H.; Huege, T.; Iarlori, M.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Jarne, C.; Johnsen, J. A.; Josebachuili, M.; Kaeaepae, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Kegl, B.; Keilhauer, B.; Keivani, A.; Kelley, J.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Kopmann, A.; Krause, R.; Krohm, N.; Kroemer, O.; Kuempel, D.; Kunka, N.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leao, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopez, R.; Lopez Casado, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Malacari, M.; Maldera, S.; Mallamaci, M.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Maris, I. C.; Marsella, G.; Martello, D.; Martina, L.; Martinez, H.; Martinez, N.; Martinez Bravo, O.; Martraire, D.; Masias Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Meissner, R.; Melissas, M.; Mello, V. B. B.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Micanovic, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Montanet, F.; Morello, C.; Mostafa, M.; Moura, C. A.; Muller, M. A.; Mueller, G.; Mueller, S.; Muenchmeyer, M.; Mussa, R.; Navarra, G.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nguyen, P. H.; Nicotra, D.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nozka, L.; Ochilo, L.; Ohnuki, T.; Oikonomou, F.; Olinto, A.; Oliveira, M.; Olmos-Gilbaja, V. M.; Pacheco, N.; PakkSelmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Papenbreer, P.; Parente, G.; Parra, A.; Patel, M.; Paul, T.; Pech, M.; Pekala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Petermann, E.; Peters, C.; Petrera, S.; Petrinca, P.; Petrov, Y.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Porter, T.; Pouryamout, J.; Pouthas, J.; Prado, R. R.; Privitera, P.; Prouza, M.; Pryke, C. L.; Purrello, V.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Randriatoamanana, R.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenua, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Robbins, S.; Roberts, M.; Rodrigues de Carvalho, W.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodriguez-Frias, M. D.; Rogozin, D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sanchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Schmidt, D.; Scholten, O.; Schoorlemmer, H.; Schovanek, P.; Schreuder, F.; Schroeder, F. G.; Schulz, A.; Schulz, J.; Schuessler, F.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Sequeiros, G.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Smialkowski, A.; Smida, R.; Smith, A. G. K.; Snow, G. R.; Sommers, P.; Sorokin, J.; Speelman, R.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanic, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijaervi, T.; Supanitsky, A. D.; Sutherland, M. S.; Sutter, M.; Swain, J.; Szadkowski, Z.; Szuba, M.; Taborda, O. A.; Tapia, A.; Tcherniakhovski, D.; Tepe, A.; Theodoro, V. M.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tome, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Trovato, E.; Trung, T. N.; Tunnicliffe, V.; Tusi, E.; Ulrich, R.; Unger, M.; Urban, M.; Valdes Galicia, J. F.; Valino, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cardenas, B.; Varnav, D. M.; Varner, G.; Vasquez, R.; Vazquez, J. R.; Vazquez, R. A.; Veberic, D.; Verkooijen, H.; Verzi, V.; Vicha, J.; Videla, M.; Villasenor, L.; Vitali, G.; Vlcek, B.; Vorenholt, H.; Vorobiov, S.; Voyvodic, L.; Wahlberg, H.; Wainberg, O.; Walker, P.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Widom, A.; Wiebusch, C.; Wiencke, L.; Wijnen, T.; Wilczynska, B.; Wilczynski, H.; Wild, N.; Winchen, T.; Wittkowski, D.; Woerner, G.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zhou, J.; Zhu, Y.; Silva, M. Zimbres; Zimmermann, B.; Ziolkowski, M.; Zuccarello, F.

    2015-01-01

    The Pierre Auger Observatory, located on a vast, high plain in western Argentina, is the world's largest cosmic ray observatory. The objectives of the Observatory are to probe the origin and characteristics of cosmic rays above 10(17) eV and to study the interactions of these, the most energetic par

  14. 双端泵Nd:YVO4固体激光器泵浦的高功率光参量振荡器%PPMgLN-based high power OPO pumped by double end pumped Nd:YVO4 laser

    Institute of Scientific and Technical Information of China (English)

    边莎莎; 吴波; 孔剑; 沈永行

    2012-01-01

    A PPMgLN-based optical parametric oscillator (OPO) pumped by a double end pumped Nd:YVO4 laser for high power laser output at 3.83 μm was reported. With two fiber pigtailed laser diodes for double end pumping, the Nd:YVO4 laser delivered a linearly polarized pulsed emission output at 1 064 nm with an average power of 23.5 W at a repetition rate of 25 kHz. With the Nd:YVO4 laser as the pump source, a PPMgLN-based OPO was developed and a mid-infrared laser output of 3.54 W at 3.83 μm was obtained. The total slope efficiency was 65.2%, and the slope efficiency from the 1.064 μm to 3.83 μm conversion was 18.1%. This system features a tight structure, relatively low cost and strong practicability. It can work stably with a power variation less than 4% within 4 hours.%报道了基于双端泵Nd:YVO4固体脉冲激光器泵浦的基于周期性畴极化反转氧化镁掺杂铌酸锂晶体(PPMgLN)的光参量振荡器(OPO).双端泵Nd:YVO4固体脉冲激光器采用激光二极管作为双端泵浦源,在25 kHz重频下获得了平均功率为23.5W的1 064nm近基模线偏振激光输出.使用该激光器泵浦一个基于PPMgLN的OPO,获得了平均功率为3.54W的3.83μm中红外激光输出.OPO的斜率效率为65.2%,其中,从1.064 μm到3.83 μm的斜率效率为18.1%.该系统结构十分紧凑、成本低、实用性强,在4h内的稳定度小于4%,具有较高的应用价值.

  15. New Geophysical Observatory in Uruguay

    Science.gov (United States)

    Sanchez Bettucci, L.; Nuñez, P.; Caraballo, R. R.; Ogando, R.

    2013-05-01

    In 2011 began the installation of the first geophysical observatory in Uruguay, with the aim of developing the Geosciences. The Astronomical and Geophysical Observatory Aiguá (OAGA) is located within the Cerro Catedral Tourist Farm (-34 ° 20 '0 .89 "S/-54 ° 42 '44.72" W, h: 270m). This has the distinction of being located in the center of the South Atlantic Magnetic Anomaly. Geologically is emplaced in a Neoproterozoic basement, in a region with scarce anthropogenic interference. The OAGA has, since 2012, with a GSM-90FD dIdD v7.0 and GSM-90F Overhauser, both of GEM Systems. In addition has a super-SID receiver provided by the Stanford University SOLAR Center, as a complement for educational purposes. Likewise the installation of a seismograph REF TEK-151-120A and VLF antenna is being done since the beginning of 2013.

  16. Micromachining of liquid crystal polymer film with frequency converted diode-pumped Nd:YVO4 laser

    Science.gov (United States)

    Li, Mingwei; Hix, Ken; Dosser, Larry R.; Hartke, Kevin; Blackshire, Jim

    2003-07-01

    Liquid crystal polymer (LCP) is a new and innovative material being used as an alternative to polyimide in the flexible circuit industry. LCP has many intrinsic benefits over polyimide including lower moisture absorption and improved dimensional stability. However, LCP is very resistant to chemical milling or etching. As a result, other methods for processing the material are being investigated including laser micromachining. In this paper, three frequency converted diode-pumped solid-state (DPSS) Nd:YVO4 lasers at 355 nm were used to micromachine a LCP film and a copper/LCP laminate. Of them, two are Q-switched lasers operating in the nanosecond regime and the other a mode-locked laser in the picosecond regime. The Q-switched lasers can be operated at pulse repetition rates of 1 to 300 kHz while the mode-locked system is operated at 80 MHz. The micromachining experiments consisted of cutting the 50 μm thick LCP film, cutting the 18 μm thick copper on the film, and drilling micro-vias through both the copper coating and the film substrate. The laser/material interactions and processing speeds were studied and compared. The results show that, compared to polyimide film of the same thickness, LCP film can be more efficiently processed by laser micromachining. In addition, each laser has a unique advantage in processing LCP based flexible circuit materials. The Q-switched lasers are more capable of processing the copper coating while the mode-locked laser can cut LCP film faster with the smallest kerf width.

  17. Improvements in geomagnetic observatory data quality

    DEFF Research Database (Denmark)

    Reda, Jan; Fouassier, Danielle; Isac, Anca

    2011-01-01

    between observatories and the establishment of observatory networks has harmonized standards and practices across the world; improving the quality of the data product available to the user. Nonetheless, operating a highquality geomagnetic observatory is non-trivial. This article gives a record...... of the current state of observatory instrumentation and methods, citing some of the general problems in the complex operation of geomagnetic observatories. It further gives an overview of recent improvements of observatory data quality based on presentation during 11th IAGA Assembly at Sopron and INTERMAGNET......Geomagnetic observatory practice and instrumentation has evolved significantly over the past 150 years. Evolution continues to be driven by advances in technology and by the need of the data user community for higher-resolution, lower noise data in near-real time. Additionally, collaboration...

  18. A scalable database model for multiparametric time series: a volcano observatory case study

    Science.gov (United States)

    Montalto, Placido; Aliotta, Marco; Cassisi, Carmelo; Prestifilippo, Michele; Cannata, Andrea

    2014-05-01

    The variables collected by a sensor network constitute a heterogeneous data source that needs to be properly organized in order to be used in research and geophysical monitoring. With the time series term we refer to a set of observations of a given phenomenon acquired sequentially in time. When the time intervals are equally spaced one speaks of period or sampling frequency. Our work describes in detail a possible methodology for storage and management of time series using a specific data structure. We designed a framework, hereinafter called TSDSystem (Time Series Database System), in order to acquire time series from different data sources and standardize them within a relational database. The operation of standardization provides the ability to perform operations, such as query and visualization, of many measures synchronizing them using a common time scale. The proposed architecture follows a multiple layer paradigm (Loaders layer, Database layer and Business Logic layer). Each layer is specialized in performing particular operations for the reorganization and archiving of data from different sources such as ASCII, Excel, ODBC (Open DataBase Connectivity), file accessible from the Internet (web pages, XML). In particular, the loader layer performs a security check of the working status of each running software through an heartbeat system, in order to automate the discovery of acquisition issues and other warning conditions. Although our system has to manage huge amounts of data, performance is guaranteed by using a smart partitioning table strategy, that keeps balanced the percentage of data stored in each database table. TSDSystem also contains modules for the visualization of acquired data, that provide the possibility to query different time series on a specified time range, or follow the realtime signal acquisition, according to a data access policy from the users.

  19. Room-temperature subnanosecond waveguide lasers in Nd:YVO4 Q-switched by phase-change VO2: A comparison with 2D materials

    Science.gov (United States)

    Nie, Weijie; Li, Rang; Cheng, Chen; Chen, Yanxue; Lu, Qingming; Romero, Carolina; Vázquez de Aldana, Javier R.; Hao, Xiaotao; Chen, Feng

    2017-01-01

    We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO4 waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66.7 mW. To compare the Q-switched laser performances by VO2 saturable absorber with those based on two-dimensional materials, the 1064-nm laser pulses have been realized in the same waveguide platform with either graphene or transition metal dichalcogenide (in this work, WS2) coated mirror. The results on 2D material Q-switched waveguide lasers have shown that the shortest pulses are with 22-ns duration, whilst the maximum output average powers reach ~161.9 mW. This work shows the obvious difference on the lasing properties based on phase-change material and 2D materials, and suggests potential applications of VO2 as low-cost saturable absorber for subnanosecond laser generation. PMID:28383017

  20. Efficient Tunable Mid-Wave Infrared Laser from 2 μm Tm,Ho:YVO4 Pumped Gain-Switched Cr2+:ZnSe Laser

    Institute of Scientific and Technical Information of China (English)

    MENG Pei-Bei; YAO Bao-Quan; LI Gang; JU You-Lun; WANG Yue-Zhu

    2011-01-01

    An efficient mid-wave infrared gain-switched Cr2+ :ZnSe laser pumped by a 2.058μm Tm,Ho:YVO4 laser is reported. As much as 3.86 W output is achieved with the pump power of 13.4 W at pulse repetition frequency of 15 kHz, corresponding to the slope efficiency of 30.9%. With a quartz birefringent filter inserted in the laser cavity and by rotating the external angle of the quartz birefringent filter, wavelength tuning range nearly from 2453nm to 2508nm with 5nm linewidth (FWHM) is also obtained.%@@ An efficient mid-wave infrared gain-switched Cr2+ :ZnSe laser pumped by a 2.058μm Tm,Ho:YVO4 laser is reported.As much as 3.86 W output is achieved with the pump power of 13.4 W at puke repetition frequency of 15 kHz,corresponding to the slope efficiency of 30.9%.With a quartz birefringent filter inserted in the laser cavity and by rotating the external angle of the quartz birefringent filter,wavelength tuning range nearly from 2453nm to 2508nm with 5nm linewidth(FWHM) is also obtained.

  1. Picosecond laser with 11 W output power at 1342 nm based on composite multiple doping level Nd:YVO4 crystal

    Science.gov (United States)

    Rodin, Aleksej M.; Grishin, Mikhail; Michailovas, Andrejus

    2016-01-01

    We report results of design and optimization of high average output power picosecond and nanosecond laser operating at 1342 nm wavelength. Developed for selective micromachining, this DPSS laser is comprised of master oscillator, regenerative amplifier and output pulse control module. Passively mode-locked by means of semiconductor saturable absorber mirror and pumped with 808 nm wavelength Nd:YVO4 master oscillator emits 12.5 ps pulses at repetition rate of 55 MHz with average output power of ∼100 mW. The four-pass confocal delay line forms a longest part of the oscillator cavity in order to suppress thermo-mechanical misalignment. Picked from the train seed pulses were injected to the cavity of regenerative amplifier based on composite Nd:YVO4 crystal with diffusion-bonded segments of multiple Nd doping concentration end-pumped at 880 nm wavelength. Laser produces pulses of ∼13 ps duration at 300 kHz repetition rate with average output power of 11 W and nearly diffraction limited beam quality of M2∼1.03. Attained high peak power ∼2.8 MW facilitates conversion to the 2nd, 3rd and 6th harmonics at 671 nm, 447 nm and 224 nm wavelengths with 80%, 50% and 15% efficiency respectively. Without seeding the regenerative amplifier transforms to electro-optically cavity-dumped Q-switched laser providing 10 ns output pulses at high repetition rates with beam propagation factor of M2∼1.06.

  2. High-Power Continuous-Wave Diode-End-Pumped Intracavity Frequency Doubled Nd:YVO4 Laser at 671 nm with a Compact Three-Element Cavity

    Institute of Scientific and Technical Information of China (English)

    ZHOU Rui; DING Xin; WEN Wu-Qi; CAI Zhi-Qiang; WANG Peng; YAO Jian-Quan

    2006-01-01

    @@ We report a high-power high-effcient continuous-wave (cw) diode-end-pumped Nd:YVO4 1342-nm laser with a short plane-parallel cavity and an efficient cw intracavity frequency-doubled red laser at 671 nm with a compact three-element cavity. At incident pump power of 20.6 W, a maximum output power of 7 W at 1342 nm is obtained with a slope efficiency of 37.3%. By inserting a type-I critical phase-matched LBO crystal as intracavity frequencydoubler, a cw red output as much as 2.85-W is achieved with an incident pump power of 16.9 W, inducing an optical-to-optical conversion efficiency of 16.9%. To the best of our knowledge, this is the highest output of diodepumped solid-state Nd:YVO4 red laser. During half an hour, the red output is very stable, and the instability of output power is less than 1%.

  3. Room-temperature subnanosecond waveguide lasers in Nd:YVO4 Q-switched by phase-change VO2: A comparison with 2D materials

    Science.gov (United States)

    Nie, Weijie; Li, Rang; Cheng, Chen; Chen, Yanxue; Lu, Qingming; Romero, Carolina; Vázquez de Aldana, Javier R.; Hao, Xiaotao; Chen, Feng

    2017-04-01

    We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO4 waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66.7 mW. To compare the Q-switched laser performances by VO2 saturable absorber with those based on two-dimensional materials, the 1064-nm laser pulses have been realized in the same waveguide platform with either graphene or transition metal dichalcogenide (in this work, WS2) coated mirror. The results on 2D material Q-switched waveguide lasers have shown that the shortest pulses are with 22-ns duration, whilst the maximum output average powers reach ~161.9 mW. This work shows the obvious difference on the lasing properties based on phase-change material and 2D materials, and suggests potential applications of VO2 as low-cost saturable absorber for subnanosecond laser generation.

  4. Volcanoes

    Science.gov (United States)

    ... Part 3 of 3) Hot Weather Tips Heat Stress in Older Adults FAQs Extreme Heat PSAs Related Links MMWR Bibliography CDC's Program Floods Flood Readiness Personal Hygiene After a Disaster Cleanup of Flood Water After a Flood Worker Safety Educational Materials Floods ...

  5. Internet-accessible, near-real-time volcano monitoring data for geoscience education: the Volcanoes Exploration Project—Pu`u `O`o

    Science.gov (United States)

    Poland, M. P.; Teasdale, R.; Kraft, K.

    2010-12-01

    Internet-accessible real- and near-real-time Earth science datasets are an important resource for geoscience education, but relatively few comprehensive datasets are available, and background information to aid interpretation is often lacking. In response to this need, the U.S. Geological Survey’s (USGS) Hawaiian Volcano Observatory, in collaboration with the National Aeronautics and Space Administration and the University of Hawai‘i, Mānoa, established the Volcanoes Exploration Project: Pu‘u ‘O‘o (VEPP). The VEPP Web site provides access, in near-real time, to geodetic, seismic, and geologic data from the Pu‘u ‘O‘o eruptive vent on Kilauea Volcano, Hawai‘i. On the VEPP Web site, a time series query tool provides a means of interacting with continuous geophysical data. In addition, results from episodic kinematic GPS campaigns and lava flow field maps are posted as data are collected, and archived Webcam images from Pu‘u ‘O‘o crater are available as a tool for examining visual changes in volcanic activity over time. A variety of background information on volcano surveillance and the history of the 1983-present Pu‘u ‘O‘o-Kupaianaha eruption puts the available monitoring data in context. The primary goal of the VEPP Web site is to take advantage of high visibility monitoring data that are seldom suitably well-organized to constitute an established educational resource. In doing so, the VEPP project provides a geoscience education resource that demonstrates the dynamic nature of volcanoes and promotes excitement about the process of scientific discovery through hands-on learning. To support use of the VEPP Web site, a week-long workshop was held at Kilauea Volcano in July 2010, which included 25 participants from the United States and Canada. The participants represented a diverse cross-section of higher learning, from community colleges to research universities, and included faculty who teach both large introductory non-major classes

  6. Radar observations of the 2009 eruption of Redoubt Volcano, Alaska: Initial deployment of a transportable Doppler radar system for volcano-monitoring

    Science.gov (United States)

    Hoblitt, R. P.; Schneider, D. J.

    2009-12-01

    The rapid detection of explosive volcanic eruptions and accurate determination of eruption-column altitude and ash-cloud movement are critical factors in the mitigation of volcanic risks to aviation and in the forecasting of ash fall on nearby communities. The U.S. Geological Survey (USGS) deployed a transportable Doppler radar during the precursory stage of the 2009 eruption of Redoubt Volcano, Alaska, and it provided valuable information during subsequent explosive events. We describe the capabilities of this new monitoring tool and present data that it captured during the Redoubt eruption. The volcano-monitoring Doppler radar operates in the C-band (5.36 cm) and has a 2.4-m parabolic antenna with a beam width of 1.6 degrees, a transmitter power of 330 watts, and a maximum effective range of 240 km. The entire disassembled system, including a radome, fits inside a 6-m-long steel shipping container that has been modified to serve as base for the antenna/radome, and as a field station for observers and other monitoring equipment. The radar was installed at the Kenai Municipal Airport, 82 km east of Redoubt and about 100 km southwest of Anchorage. In addition to an unobstructed view of the volcano, this secure site offered the support of the airport staff and the City of Kenai. A further advantage was the proximity of a NEXRAD Doppler radar operated by the Federal Aviation Administration. This permitted comparisons with an established weather-monitoring radar system. The new radar system first became functional on March 20, roughly a day before the first of nineteen explosive ash-producing events of Redoubt between March 21 and April 4. Despite inevitable start-up problems, nearly all of the events were observed by the radar, which was remotely operated from the Alaska Volcano Observatory office in Anchorage. The USGS and NEXRAD radars both detected the eruption columns and tracked the directions of drifting ash clouds. The USGS radar scanned a 45-degree sector

  7. Combining Volcano Monitoring Timeseries Analyses with Bayesian Belief Networks to Update Hazard Forecast Estimates

    Science.gov (United States)

    Odbert, Henry; Hincks, Thea; Aspinall, Willy

    2015-04-01

    Volcanic hazard assessments must combine information about the physical processes of hazardous phenomena with observations that indicate the current state of a volcano. Incorporating both these lines of evidence can inform our belief about the likelihood (probability) and consequences (impact) of possible hazardous scenarios, forming a basis for formal quantitative hazard assessment. However, such evidence is often uncertain, indirect or incomplete. Approaches to volcano monitoring have advanced substantially in recent decades, increasing the variety and resolution of multi-parameter timeseries data recorded at volcanoes. Interpreting these multiple strands of parallel, partial evidence thus becomes increasingly complex. In practice, interpreting many timeseries requires an individual to be familiar with the idiosyncrasies of the volcano, monitoring techniques, configuration of recording instruments, observations from other datasets, and so on. In making such interpretations, an individual must consider how different volcanic processes may manifest as measureable observations, and then infer from the available data what can or cannot be deduced about those processes. We examine how parts of this process may be synthesised algorithmically using Bayesian inference. Bayesian Belief Networks (BBNs) use probability theory to treat and evaluate uncertainties in a rational and auditable scientific manner, but only to the extent warranted by the strength of the available evidence. The concept is a suitable framework for marshalling multiple strands of evidence (e.g. observations, model results and interpretations) and their associated uncertainties in a methodical manner. BBNs are usually implemented in graphical form and could be developed as a tool for near real-time, ongoing use in a volcano observatory, for example. We explore the application of BBNs in analysing volcanic data from the long-lived eruption at Soufriere Hills Volcano, Montserrat. We show how our method

  8. The Arecibo Observatory Space Academy

    Science.gov (United States)

    Rodriguez-Ford, Linda A.; Zambrano-Marin, Luisa; Petty, Bryan M.; Sternke, Elizabeth; Ortiz, Andrew M.; Rivera-Valentin, Edgard G.

    2015-11-01

    The Arecibo Observatory Space Academy (AOSA) is a ten (10) week pre-college research program for students in grades 9-12. Our mission is to prepare students for academic and professional careers by allowing them to receive an independent and collaborative research experience on topics related to space and aide in their individual academic and social development. Our objectives are to (1) Supplement the student’s STEM education via inquiry-based learning and indirect teaching methods, (2) Immerse students in an ESL environment, further developing their verbal and written presentation skills, and (3) To foster in every student an interest in science by exploiting their natural curiosity and knowledge in order to further develop their critical thinking and investigation skills. AOSA provides students with the opportunity to share lectures with Arecibo Observatory staff, who have expertise in various STEM fields. Each Fall and Spring semester, selected high school students, or Cadets, from all over Puerto Rico participate in this Saturday academy where they receive experience designing, proposing, and carrying out research projects related to space exploration, focusing on four fields: Physics/Astronomy, Biology, Engineering, and Sociology. Cadets get the opportunity to explore their topic of choice while practicing many of the foundations of scientific research with the goal of designing a space settlement, which they present at the NSS-NASA Ames Space Settlement Design Contest. At the end of each semester students present their research to their peers, program mentors, and Arecibo Observatory staff. Funding for this program is provided by NASA SSERVI-LPI: Center for Lunar Science and Exploration with partial support from the Angel Ramos Visitor Center through UMET and management by USRA.

  9. The Liverpool Bay Coastal Observatory

    Science.gov (United States)

    Howarth, John; Palmer, Matthew

    2011-11-01

    A pilot Coastal Observatory has been established in Liverpool Bay which integrates (near) real-time measurements with coupled models and whose results are displayed on the web. The aim is to understand the functioning of coastal seas, their response to natural forcing and the consequences of human activity. The eastern Irish Sea is an apt test site, since it encompasses a comprehensive range of processes found in tidally dominated coastal seas, including near-shore physical and biogeochemical processes influenced by estuarine inflows, where both vertical and horizontal gradients are important. Applications include hypernutrification, since the region receives significantly elevated levels of nutrient inputs, shoreline management (coastal flooding and beach erosion/accretion), and understanding present conditions to predict the impact of climate change (for instance if the number and severity of storms, or of high or low river flows, change). The integrated measurement suite which started in August 2002 covers a range of space and time scales. It includes in situ time series, four to six weekly regional water column surveys, an instrumented ferry, a shore-based HF radar system measuring surface currents and waves, coastal tide gauges and visible and infra-red satellite data. The time series enable definition of the seasonal cycle, its inter-annual variability and provide a baseline from which the relative importance of events can be quantified. A suite of nested 3D hydrodynamic, wave and ecosystem models is run daily, focusing on the observatory area by covering the ocean/shelf of northwest Europe (at 12-km resolution) and the Irish Sea (at 1.8 km), and Liverpool Bay at the highest resolution of 200 m. The measurements test the models against events as they happen in a truly 3D context. All measurements and model outputs are displayed freely on the Coastal Observatory website (http://cobs.pol.ac.uk) for an audience of researchers, education, coastal managers and the

  10. Influence of y3+, Bi3+ Content on Photoluminescence of YVO4 : Dy3+ Phosphor Induced by Ultraviolet Excitation%Influence of y3+,Bi3+ Content on Photoluminescence of YVO4:Dy3+ Phosphor Induced by Ultraviolet Excitation

    Institute of Scientific and Technical Information of China (English)

    HE Yu-yang; ZHAO Mai-qun; SONG Yan-yan; ZHAO Gao-yang; LI Feng

    2011-01-01

    YxVO4:0.01Dy3+ and Y0.99-xVO4:0.01Dy3+,xBi3+ phosphors were synthesized by chemical coprecipitation method.Their crystal structure,micromorphology and photoluminescence (PL) properties were investigated by X-ray diffraction (XRD),scan electron microscopy (SEM) and spectrofluorometer.YxVO4:0.01Dy3+ and Y0.99-xVO4:0.01Dy3+,xBi3+ phosphors have a broad excitation band from about 250 to 350 nm including a strongest peak at about 310 nm.Under its excitation,the emission spectra exhibits two sharp peaks,one of which centered at about 483 nm for 4 F9/2→6 H15/2 transition of Dy3+ and the other at about 574nm due to the 4F9/2→6H13/2 transition of Dy3+.For YxVO4:0.01Dy3+ (x=0.94,0.97,0.99,1.01,1.03)phosphor,with increasing value of x,the body color of phosphor changes from yellow to white and the strongest peak in the excitation spectra shifts a little to shorter wavelength.It is detrimental to luminous intensity when Y3+ content deviates stoichiometric ratio.For Y0.99-xVO4:0.01Dy3+,xBi3+ (x=0.01,0.05,0.1,0.15,0.2,0.25) phosphor,the samples have extraneous bismuth vanadium oxide phase except for the major tetragonal zircon structure when x≥0.20.With increasing value of x,the band edge in the excitation spectra shifts to longer wavelength,the excitation intensity and luminous intensity increase early and decrease late.When the value of x is 0.01,the intensities increase evidently.In addition,the influence of Y3+ or Bi3+ on the color temperature of emission and micromorphology of YVO4:Dy3+ is slight.

  11. Light pollution around Tonantzintla Observatory

    Science.gov (United States)

    Vázquez-Mata, José A.; Hernández-Toledo, Héctor M.; Martínez-Vázquez, Luis A.; Pani-Cielo, Atanacio

    2011-06-01

    Being close to the cities of Puebla to east and Cholula to the north, both having potential for large growth, the National Astronomical Observatory in Tonantzintla (OAN-Tonantzintla) faces the danger of deteriorating its sky conditions even more. In order to maintain competitiveness for education and scientific programs, it is important to preserve the sky brightness conditions. through: 1) our awareness of the night sky characteristics in continuous monitoring campaigns, doing more measurements over the next years to monitor changes and 2) encouraging local authorities about the need to regulate public lighting at the same time, showing them the benefits of such initiatives when well planed and correctly implemented.

  12. Gamma ray observatory productivity showcase

    Science.gov (United States)

    Davis, R. L.; Molgaard, D. A.

    1985-01-01

    The Gamma Ray Observatory (GRO) Program has been proclaimed to be the showcase productivity program for NASA and TRW. Among the multiple disciplines of a large-scale program, there is opportunity and need for improved efficiency, effectiveness, and reduction in the cost of doing business. The efforts and tools that will or have been implemented to achieve this end are described. Since the GRO Program is mainly an engineering program with the build of one satellite, the primary emphasis is placed on improving the efficiency and quality of management and engineering.

  13. India-based Neutrino Observatory

    Indian Academy of Sciences (India)

    Naba K Mondal; for the INO Collaboration

    2012-11-01

    The current status of the India-based Neutrino Observatory (INO) is summarized. The main physics goals are described followed by the motivation for building a magnetized iron calorimetric (ICAL) detector. The charge identification capability of ICAL would make it complementary to large water Cerenkov and other detectors worldwide. The status of the design of the 50 kt magnet, the construction of a prototype ICAL detector, the experience with resistive plate chambers which will be the active elements in ICAL and the status of the associated electronics and data acquisition system are discussed.

  14. Lahar hazards at Agua volcano, Guatemala

    Science.gov (United States)

    Schilling, S.P.; Vallance, J.W.; Matías, O.; Howell, M.M.

    2001-01-01

    At 3760 m, Agua volcano towers more than 3500 m above the Pacific coastal plain to the south and 2000 m above the Guatemalan highlands to the north. The volcano is within 5 to 10 kilometers (km) of Antigua, Guatemala and several other large towns situated on its northern apron. These towns have a combined population of nearly 100,000. It is within about 20 km of Escuintla (population, ca. 100,000) to the south. Though the volcano has not been active in historical time, or about the last 500 years, it has the potential to produce debris flows (watery flows of mud, rock, and debris—also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

  15. Volcanoes muon imaging using Cherenkov telescopes

    CERN Document Server

    Catalano, Osvaldo; Mineo, Teresa; Cusumano, Giancarlo; Maccarone, Maria Concetta; Pareschi, Giovanni

    2015-01-01

    A detailed understanding of a volcano inner structure is one of the key-points for the volcanic hazards evaluation. To this aim, in the last decade, geophysical radiography techniques using cosmic muon particles have been proposed. By measuring the differential attenuation of the muon flux as a function of the amount of rock crossed along different directions, it is possible to determine the density distribution of the interior of a volcano. Up to now, a number of experiments have been based on the detection of the muon tracks crossing hodoscopes, made up of scintillators or nuclear emulsion planes. Using telescopes based on the atmospheric Cherenkov imaging technique, we propose a new approach to study the interior of volcanoes detecting the Cherenkov light produced by relativistic cosmic-ray muons that survive after crossing the volcano. The Cherenkov light produced along the muon path is imaged as a typical annular pattern containing all the essential information to reconstruct particle direction and energ...

  16. Radial anisotropy ambient noise tomography of volcanoes

    Science.gov (United States)

    Mordret, Aurélien; Rivet, Diane; Shapiro, Nikolai; Jaxybulatov, Kairly; Landès, Matthieu; Koulakov, Ivan; Sens-Schönfelder, Christoph

    2016-04-01

    The use of ambient seismic noise allows us to perform surface-wave tomography of targets which could hardly be imaged by other means. The frequencies involved (~ 0.5 - 20 s), somewhere in between active seismic and regular teleseismic frequency band, make possible the high resolution imaging of intermediate-size targets like volcanic edifices. Moreover, the joint inversion of Rayleigh and Love waves dispersion curves extracted from noise correlations allows us to invert for crustal radial anisotropy. We present here the two first studies of radial anisotropy on volcanoes by showing results from Lake Toba Caldera, a super-volcano in Indonesia, and from Piton de la Fournaise volcano, a hot-spot effusive volcano on the Réunion Island (Indian Ocean). We will see how radial anisotropy can be used to infer the main fabric within a magmatic system and, consequently, its dominant type of intrusion.

  17. A field guide to Newberry Volcano, Oregon

    Science.gov (United States)

    Jenson, Robert A.; Donnelly-Nolan, Julie M.; McKay, Daniele

    2009-01-01

    Newberry Volcano is located in central Oregon at the intersection of the Cascade Range and the High Lava Plains. Its lavas range in age from ca. 0.5 Ma to late Holocene. Erupted products range in composition from basalt through rhyolite and cover ~3000 km2. The most recent caldera-forming eruption occurred ~80,000 years ago. This trip will highlight a revised understanding of the volcano's history based on new detailed geologic work. Stops will also focus on evidence for ice and flooding on the volcano, as well as new studies of Holocene mafic eruptions. Newberry is one of the most accessible U.S. volcanoes, and this trip will visit a range of lava types and compositions including tholeiitic and calc-alkaline basalt flows, cinder cones, and rhyolitic domes and tuffs. Stops will include early distal basalts as well as the youngest intracaldera obsidian flow.

  18. ``Route of astronomical observatories'' project: Classical observatories from the Renaissance to the rise of astrophysics

    Science.gov (United States)

    Wolfschmidt, Gudrun

    2016-10-01

    Observatories offer a good possibility for serial transnational applications. For example one can choose groups like baroque or neoclassical observatories, solar physics observatories or a group of observatories equipped with the same kind of instruments or made by famous firms. I will discuss what has been achieved and show examples, like the route of astronomical observatories, the transition from classical astronomy to modern astrophysics. I will also discuss why the implementation of the World Heritage & Astronomy initiative is difficult and why there are problems to nominate observatories for election in the national tentative lists.

  19. Real-time GNSS volcano deformation monitoring (Invited)

    Science.gov (United States)

    Lisowski, M.; Langbein, J. O.; Hudnut, K. W.

    2013-12-01

    We present comparisons of the precision obtained from several alternative real-time GNSS processing methods, and show how offsets caused by snow and ice on an antenna can be automatically identified in real time using signal-to-noise ratio (SNR) data. We monitor ground deformation using continuous GNSS stations installed on several volcanoes in the Cascade Range and elsewhere, and many of these stations transmit high-rate (1s) data in real-time. We examine real-time, high-rate station position solutions obtained with two implementations of centralized RTNet (GPS Solutions, Inc.) processing, and find that the precision is roughly the same for ambiguity-fixed network solutions and for ambiguity-fixed precise point position solutions (PPPAR). The PPPAR method uses satellite clock corrections provided by GPS Solutions from a network of Plate Boundary Observatory (PBO) stations in western Oregon. The precision of network solutions that include GPS and GLONASS data is similar to the GPS-only solutions, except at stations with a relatively poor view of the sky. An alternative method of processing the real-time GPS data uses clock corrections transmitted directly to the receiver, which then autonomously calculates and transmits positions. We will compare our RTNet results with autonomous point position solutions calculated using Trimble's CenterPoint RTX corrections. RTX performance in repeated, controlled, large antenna-motion tests by USGS and UNAVCO indicates that it meets requirements of USGS volcano-monitoring applications; more thorough testing and performance checks on an ongoing basis would be desirable. GNSS antennas on volcanoes often become temporarily coated with ice or buried by snow in the winter. In these situations, signal delays introduce an apparent offset in the monitoring station's position. We address this problem by implementing in real time a technique developed by Kristine Larson that uses changes in the signal-to-noise ratio (SNR) of GNSS signals

  20. A search for the volcanomagnetic signal at Deception volcano (South Shetland I., Antarctica

    Directory of Open Access Journals (Sweden)

    J. M. Ibáñez

    1997-06-01

    Full Text Available After the increase in seismic activity detected during the 1991-1992 summer survey at Deception Island, the continuous measurement of total magnetic intensity was included among the different techniques used to monitor this active volcano. The Polish geomagnetic observatory Arctowski, located on King George Island, served as a reference station, and changes in the differences between the daily mean values at both stations were interpreted as indicators of volcanomagnetic effects at Deception. A magnetic station in continuous recording mode was also installed during the 1993-1994 and 1994-1995 surveys. During the latter, a second magnetometer was deployed on Deception Island, and a third one in the vicinity of the Spanish Antarctic Station on Livingston Island (at a distance of 35 km and was used as a reference station. The results from the first survey suggest that a small magma injection, responsible for the seismic re-activation, could produce a volcanomagnetic effect, detected as a slight change in the difference between Deception and Arctowski. On the other hand, a long term variation starting at that moment seems to indicate a thermomagnetic effect. However the short register period of only two stations do not allow the sources to be modelled. The future deployment of a magnetic array during the austral summer surveys, throughout the volcano, and of a permanent geomagnetic observatory at Livingston I. is aimed at further observations of magnetic transients of volcanic origin at Deception Island.

  1. Protection of the Guillermo Haro Astrophysical Observatory

    Science.gov (United States)

    Carrasco, E.; Carraminana, A. P.

    The Guillermo Haro Astrophysical Observatory, with a 2m telescope, is one of only two professional observatories in Mexico. The observatory, run by the InstitutoNacional de Astrofisica, Optica y Electronica (INAOE), is located in the north of Mexico, in Cananea, Sonora. Since 1995 the observatory has faced the potential threat of pollution by an open cast mine to be opened at 3kms from the observatory. In the absence of national or regional laws enforcing protection to astronomical sites in Mexico, considerable effort has been needed to guarantee the conditions of the site. We present the studies carried out to ensure the protection of the Guillermo Haro Observatory from pollution due to dust, light and vibrations.

  2. EMSO: European multidisciplinary seafloor observatory

    Energy Technology Data Exchange (ETDEWEB)

    Favali, Paolo [Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via di Vigna Murata 605, 00143 Roma (Italy); Universita degli Studi di Roma ' La Sapienza' , P.le Aldo Moro 5, 00185 Roma (Italy)], E-mail: emsopp@ingv.it; Beranzoli, Laura [Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via di Vigna Murata 605, 00143 Roma (Italy)

    2009-04-11

    EMSO has been identified by the ESFRI Report 2006 as one of the Research Infrastructures that European members and associated states are asked to develop in the next decades. It will be based on a European-scale network of multidisciplinary seafloor observatories from the Arctic to the Black Sea with the aim of long-term real-time monitoring of processes related to geosphere/biosphere/hydrosphere interactions. EMSO will enhance our understanding of processes, providing long time series data for the different phenomenon scales which constitute the new frontier for study of Earth interior, deep-sea biology and chemistry, and ocean processes. The development of an underwater network is based on past EU projects and is supported by several EU initiatives, such as the on-going ESONET-NoE, aimed at strengthening the ocean observatories' scientific and technological community. The EMSO development relies on the synergy between the scientific community and industry to improve European competitiveness with respect to countries such as USA, Canada and Japan. Within the FP7 Programme launched in 2006, a call for Preparatory Phase (PP) was issued in order to support the foundation of the legal and organisational entity in charge of building up and managing the infrastructure, and coordinating the financial effort among the countries. The EMSO-PP project, coordinated by the Italian INGV with participation by 11 institutions from as many European countries, started in April 2008 and will last four years.

  3. The International Virtual Observatory Alliance

    Science.gov (United States)

    Kembhavi, Ajit

    Over the last few years Astronomical Virtual Observatory (VO) projects have been initiated in several countries. The aim of these projects is to make astronomical data gathered in all ways and in all places available to every person who may need it along with appropriate software for data access analysis visualization and interpretation. The VO projects largely work in their own ways and with their own priorities shaped by scientific interests and available resources. For the VO concept to be successful these efforts have to be meshed together seamlessly through interoperability standards new data formats which take into account emerging technology and software developed in forms which are largely independent of platforms and operating systems. It is also necessary to develop computing grids which will cross national and project boundaries and can be accessed by any researcher who wishes to use the data mountains. This process of integration and assimilation is to be fostered through international alliances spanning various VO efforts. I will describe in my talk formal alliances like the International Virtual Observatory as well as specific bilateral and multilateral collaborations between individuals institutions or projects and the VO related products that have been launched through these collaborations.

  4. Changes of biogeochemical activities before and after significant mud displacement at the Håkon Mosby Mud Volcano (HMMV)

    Science.gov (United States)

    Felden, J.; Wenzhöfer, F.; Yoerger, D.; Camilli, R.; German, C.; Olu, K.; Feseker, T.; de Beer, D.; Boetius, A.

    2012-04-01

    The Håkon Mosby Mud Volcano (72°N, 14° 43' E, 1250 m water depth) was studied for a period of a year by the Long-term Observatory On Mud-volcano Eruptions (LOOME) in 2009-2010, to investigate temporal variations of mud volcanism and consequences for biogeochemical processes. The HMMV is a highly active methane cold seep ecosystem characterized by high rates of methane efflux. It hosts different chemosynthetic communities such as thiotrophic bacterial mats and siboglinid tubeworm assemblages. This study focuses on changes in community composition and biogeochemical activity such as methane emission, total benthic oxygen uptake, microbial methane and sulfate consumption before and after a major mud displacement recorded by LOOME. The sensor-enabled long-term observations of the HMMV habitats were combined with short-term analyses before and after the displacement events by ROVs QUEST (MARUM) and GENESIS (University of Gent), the AUV Sentry (WHOI) equipped with a multibeam and subbottom profiler, CTD and photographic unit as well as with a mass spectrometer. We found shifts in the distribution patterns of chemosynthetic communities and also substantial changes in their activity, consistent with changes in temperature gradients. This study was sponsored by the EU-Projects HERMIONE "Hotspot Ecosystem Research and Man's Impact on European Seas", and ESONET "European Seas Observatory Network" (Demonstration Mission LOOME "Long term observations on mud volcano eruptions").

  5. Global Volcano Model: progress towards an international co-ordinated network for volcanic hazard and risk

    Science.gov (United States)

    Loughlin, Susan

    2013-04-01

    GVM is a growing international collaboration that aims to create a sustainable, accessible information platform on volcanic hazard and risk. GVM is a network that aims to co-ordinate and integrate the efforts of the international volcanology community. Major international initiatives and partners such as the Smithsonian Institution - Global Volcanism Program, State University of New York at Buffalo - VHub, Earth Observatory of Singapore - WOVOdat and many others underpin GVM. Activities currently include: design and development of databases of volcano data, volcanic hazards, vulnerability and exposure with internationally agreed metadata standards; establishment of methodologies for analysis of the data (e.g. hazard and exposure indices) to inform risk assessment; development of complementary hazards models and create relevant hazards and risk assessment tools. GVM acts through establishing task forces to deliver explicit deliverables in finite periods of time. GVM has a task force to deliver a global assessment of volcanic risk for UN ISDR, a task force for indices, and a task force for volcano deformation from satellite observations. GVM is organising a Volcano Best Practices workshop in 2013. A recent product of GVM is a global database on large magnitude explosive eruptions. There is ongoing work to develop databases on debris avalanches, lava dome hazards and ash hazard. GVM aims to develop the capability to anticipate future volcanism and its consequences.

  6. Lahar-hazard zonation for San Miguel volcano, El Salvador

    Science.gov (United States)

    Major, J.J.; Schilling, S.P.; Pullinger, C.R.; Escobar, C.D.; Chesner, C.A.; Howell, M.M.

    2001-01-01

    San Miguel volcano, also known as Chaparrastique, is one of many volcanoes along the volcanic arc in El Salvador. The volcano, located in the eastern part of the country, rises to an altitude of about 2130 meters and towers above the communities of San Miguel, El Transito, San Rafael Oriente, and San Jorge. In addition to the larger communities that surround the volcano, several smaller communities and coffee plantations are located on or around the flanks of the volcano, and the PanAmerican and coastal highways cross the lowermost northern and southern flanks of the volcano. The population density around San Miguel volcano coupled with the proximity of major transportation routes increases the risk that even small volcano-related events, like landslides or eruptions, may have significant impact on people and infrastructure. San Miguel volcano is one of the most active volcanoes in El Salvador; it has erupted at least 29 times since 1699. Historical eruptions of the volcano consisted mainly of relatively quiescent emplacement of lava flows or minor explosions that generated modest tephra falls (erupted fragments of microscopic ash to meter sized blocks that are dispersed into the atmosphere and fall to the ground). Little is known, however, about prehistoric eruptions of the volcano. Chemical analyses of prehistoric lava flows and thin tephra falls from San Miguel volcano indicate that the volcano is composed dominantly of basalt (rock having silica content

  7. Worldwide R&D of Virtual Observatory

    CERN Document Server

    Cui, Chenzhou

    2007-01-01

    Virtual Observatory (VO) is a data intensive online astronomical research and education environment, taking advantages of advanced information technologies to achieve seamless and uniform access to astronomical information. The concept of VO was introduced in late of 1990s to meet challenges brought up with data avalanche in astronomy. This paper reviews current status of International Virtual Observatory Alliance, technical highlights from world wide VO projects, and a brief introduction of Chinese Virtual Observatory.

  8. A new Magnetic Observatory in Pantanal - Brazil

    Science.gov (United States)

    Siqueira, F.; Pinheiro, K.; Linthe, H.

    2013-05-01

    The aim of a Magnetic Observatory is to register the variations of the Earth's magnetic field in a long temporal scale. Using this data it is possible to study field variations of both external and internal origins. The external variations concern interactions between the magnetosphere and the solar wind, in general are measured in a short time scale. The internal field generated by convection of a high electrical conductivity fluid in the external core by a mechanism known as the geodynamo. Usually the internal field time variations are longer than in the external field and are called secular variations. Measurements carried out over the last century suggest that field intensity is decreasing rapidly. The decreasing of the field's intensity is not the same around the globe, especially at the SAMA (South Atlantic Magnetic Anomaly) regions, where this reduction is occurring faster. The global distribution of magnetic observatories is uneven, with few observatories in South America. In Brazil, there are three magnetic observatories, but only Vassouras Observatory (VSS- RJ) is part of the INTERMAGNET network. The National Observatory has plans to install seven new observatories in Brazil. Pantanal was the chosen location for installing the first observatory because of its privileged location, close to the SAMA region, and its data can contribute to more information about its origin. We followed the procedures suggested by the IAGA to build this observatory. The first step is to perform a magnetic survey in order to avoid strong magnetic gradients in the location where the absolute and variometers houses will be installed. The next step, the construction of the observatory, includes the selection of special non-magnetic material for the variometer and absolute houses. All materials used were previously tested using a proton magnetometer GSM-19. After construction of the whole infrastructure, the equipment was installed. This Project is a cooperation between Brazilian

  9. Byurakan Astrophysical Observatory as Cultural Centre

    Science.gov (United States)

    Mickaelian, A. M.; Farmanyan, S. V.

    2017-07-01

    NAS RA V. Ambartsumian Byurakan Astrophysical Observatory is presented as a cultural centre for Armenia and the Armenian nation in general. Besides being scientific and educational centre, the Observatory is famous for its unique architectural ensemble, rich botanical garden and world of birds, as well as it is one of the most frequently visited sightseeing of Armenia. In recent years, the Observatory has also taken the initiative of the coordination of the Cultural Astronomy in Armenia and in this field, unites the astronomers, historians, archaeologists, ethnographers, culturologists, literary critics, linguists, art historians and other experts. Keywords: Byurakan Astrophysical Observatory, architecture, botanic garden, tourism, Cultural Astronomy.

  10. Output Characteristics of LD End-pumping Nd:YVO_4 Laser with Pulse Repetition Rates up to 1 kHz%LD端面抽运1KHz电光调Q Nd:YVO_4激光器输出功率特性研究

    Institute of Scientific and Technical Information of China (English)

    宋标; 李传起; 谢爱根; 王铁邦

    2009-01-01

    A laser diode (LD) continuous-wave (CW) end-pumping high repetition rate electro-optic ( EO) Q-switching Nd : YVO_4 laser was experimentally and theoretically studied. In experiments , using BBO single crystal as an EO Q-switch,with 10 W pump power ,about 170 mW average power was obtained at 1 kHz repetition rate. The dips in the output power curves were analyzed, A reasonable explaination was given and a way of improving the output was pointed out through the graphic analysis of the transmitting and transforming circle.%报道了全固态激光器连续抽运高重复率电光调Q Nd:YVO_4激光器的实验和理论分析结果,用BBO晶体作电光调Q元件,在激光二极管(LD)端面抽运Nd:YVO_4激光器中实现了较高重复率的电光调Q输出.实验中在1 kHz重复率下,抽运功率为10 W时,平均功率超过170 mW.对输出功率曲线中的凹陷现象进行了分析,指出了制约激光器的内在诸因素,并用传播圆-变换圆图解分析方法给出了合理的解释.

  11. EARTHQUAKES - VOLCANOES (Causes - Forecast - Counteraction)

    Science.gov (United States)

    Tsiapas, Elias

    2014-05-01

    Earthquakes and volcanoes are caused by: 1)Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2)Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3)The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is

  12. The Museum of Vesuvius Observatory and its public. Years 2005 - 2008

    Science.gov (United States)

    De Lucia, Maddalena; Ottaiano, Mena; Limoncelli, Bianca; Parlato, Luigi; Scala, Omar; Siviglia, Vittoria

    2010-05-01

    The museum of Vesuvius Observatory was created through the enlargement and updating of a permanent exhibition called "Vesuvius: 2000 years of observations", set up in 2000 with the aim of make citizens aware of volcanic phenomena, volcanic hazard and surveillance of active volcanoes in high risk areas, such as Naples and surroundings. The museum is located in the nineteenth-century historical building of the Vesuvius Observatory, the first volcanological observatory in the world, currently part of the National Institute of Geophysics and Volcanology. In the museum the dominant theme is the volcano Vesuvius: along the exhibition scientific issues are strictly interlaced with historical, archaeological and literary topics. The exhibition path begins with the presentation of eruptive phenomena, and related hazard for people and things. It traces the eruptive history of Somma-Vesuvius pointing out the most famous eruptions, occurred in 79 AD and 1944, and the methodologies used by volcanologists to define the eruptive history of a volcano through the study of its products. In the octagonal room the products of effusive and explosive eruptions, and minerals formed in volcanic environments, are displayed. The path, consisting of panels and video on big screen, is enriched by the exhibition of historical documents as the geological map of Somma-Vesuvius by Henry James Johnston-Lavis and of copies of Ercolano and Pompeii casts. Also historical scientific instruments once used for surveillance are on display, including the first electromagnetic seismograph, built in 1856 by Luigi Palmieri, director of the Vesuvius Observatory from 1855 to 1896. The tour ends with a practical experience of simulation of an earthquake. Communication tools used in the museum are basically video and panels. The museum admission is free; visitors enter the museum by guided tours only. Since the year 2000 checking of visiting public was carried out, either through booking requests received by the

  13. Spreading and collapse of big basaltic volcanoes

    Science.gov (United States)

    Puglisi, Giuseppe; Bonforte, Alessandro; Guglielmino, Francesco; Peltier, Aline; Poland, Michael

    2016-04-01

    Among the different types of volcanoes, basaltic ones usually form the most voluminous edifices. Because volcanoes are growing on a pre-existing landscape, the geologic and structural framework of the basement (and earlier volcanic landforms) influences the stress regime, seismicity, and volcanic activity. Conversely, the masses of these volcanoes introduce a morphological anomaly that affects neighboring areas. Growth of a volcano disturbs the tectonic framework of the region, clamps and unclamps existing faults (some of which may be reactivated by the new stress field), and deforms the substratum. A volcano's weight on its basement can trigger edifice spreading and collapse that can affect populated areas even at significant distance. Volcano instability can also be driven by slow tectonic deformation and magmatic intrusion. The manifestations of instability span a range of temporal and spatial scales, ranging from slow creep on individual faults to large earthquakes affecting a broad area. In the frame of MED-SVU project, our work aims to investigate the relation between basement setting and volcanic activity and stability at three Supersite volcanoes: Etna (Sicily, Italy), Kilauea (Island of Hawaii, USA) and Piton de la Fournaise (La Reunion Island, France). These volcanoes host frequent eruptive activity (effusive and explosive) and share common features indicating lateral spreading and collapse, yet they are characterized by different morphologies, dimensions, and tectonic frameworks. For instance, the basaltic ocean island volcanoes of Kilauea and Piton de la Fournaise are near the active ends of long hotspot chains while Mt. Etna has developed at junction along a convergent margin between the African and Eurasian plates and a passive margin separating the oceanic Ionian crust from the African continental crust. Magma supply and plate velocity also differ in the three settings, as to the sizes of the edifices and the extents of their rift zones. These

  14. Virtual Energetic Particle Observatory (VEPO)

    Science.gov (United States)

    Cooper, John F.; Lal, Nand; McGuire, Robert E.; Szabo, Adam; Narock, Thomas W.; Armstrong, Thomas P.; Manweiler, Jerry W.; Patterson, J. Douglas; Hill, Matthew E.; Vandergriff, Jon D.; McKibben, Robert B.; Lopate, Clifford; Tranquille, Cecil

    2008-01-01

    The Virtual Energetic Particle Observatory (VEPO) focuses on improved discovery, access, and usability of heliospheric energetic particle and ancillary data products from selected spacecraft and sub-orbital instruments of the heliophysics data environment. The energy range of interest extends over the full range of particle acceleration from keV energies of suprathermal seed particles to GeV energies of galactic cosmic ray particles. Present spatial coverage is for operational and legacy spacecraft operating from the inner to the outer heliosphere, e.g. from measurements by the two Helios spacecraft to 0.3 AU to the inner heliosheath region now being traversed by the two Voyager spacecraft. This coverage will eventually be extended inward to ten solar radii by the planned NASA solar probe mission and at the same time beyond the heliopause into the outer heliosheath by continued Voyager operations. The geospace fleet of spacecraft providing near-Earth interplanetary measurements, selected magnetospheric spacecraft providing direct measurements of penetrating interplanetary energetic particles, and interplanetary cruise measurements from planetary spacecraft missions further extend VEPO resources to the domain of geospace and planetary interactions. Ground-based (e.g., neutron monitor) and high-altitude suborbital measurements can expand coverage to the highest energies of galactic cosmic rays affected by heliospheric interaction and of solar energetic particles. Science applications include investigation of solar flare and coronal mass ejection events. acceleration and transport of interplanetary particles within the inner heliosphere, cosmic ray interactions with planetary surfaces and atmospheres, sources of suprathermal and anomalous cosmic ray ions in the outer heliosphere, and solar cycle modulation of galactic cosmic rays. Robotic and human exploration, and eventual habitation, of planetary and space environments beyond the Earth require knowledge of radiation

  15. Volcanoes of México: An Interactive CD-ROM From the Smithsonian's Global Volcanism Program

    Science.gov (United States)

    Siebert, L.; Kimberly, P.; Calvin, C.; Luhr, J. F.; Kysar, G.

    2002-12-01

    The Smithsonian Institution's Global Volcanism Program is nearing completion of an interactive CD-ROM, the Volcanoes of México. This CD is the second in a series sponsored by the U.S. Department of Energy Office of Geothermal Technologies to collate Smithsonian data on Quaternary volcanism as a resource for the geothermal community. It also has utility for those concerned with volcanic hazard and risk mitgation as well as an educational tool for those interested in Mexican volcanism. We acknowledge the significant contributions of many Mexican volcanologists to the eruption reports, data, and images contained in this CD, in particular those contributions of the Centro Nacional de Prevencion de Desastres (CENAPRED), the Colima Volcano Observatory of the University of Colima, and the Universidad Nacional Autónoma de México (UNAM). The Volcanoes of México CD has a format similar to that of an earlier Smithsonian CD, the Volcanoes of Indonesia, but also shows Pleistocene volcanic centers and additional data on geothermal sites. A clickable map of México shows both Holocene and Pleistocene volcanic centers and provides access to individual pages on 67 volcanoes ranging from Cerro Prieto in Baja California to Tacaná on the Guatemalan border. These include geographic and geologic data on individual volcanoes (as well as a brief paragraph summarizing the geologic history) along with tabular eruption chronologies, eruptive characteristics, and eruptive volumes, when known. Volcano data are accessible from both geographical and alphabetical searches. A major component of the CD is more than 400 digitized images illustrating the morphology of volcanic centers and eruption processes and deposits, providing a dramatic visual primer to the country's volcanoes. Images of specific eruptions can be directly linked to from the eruption chronology tables. The Volcanoes of México CD includes monthly reports and associated figures and tables cataloging volcanic activity in M

  16. The Merapi Interactive Project: Offering a Fancy Cross-Disciplinary Scientific Understanding of Merapi Volcano to a Wide Audience.

    Science.gov (United States)

    Morin, J.; Kerlow, I.

    2015-12-01

    The Merapi volcano is of great interest to a wide audience as it is one of the most dangerous volcanoes worldwide and a beautiful touristic spot. The scientific literature available on that volcano both in Earth and Social sciences is rich but mostly inaccessible to the public because of the scientific jargon and the restricted database access. Merapi Interactive aims at developing clear information and attractive content about Merapi for a wide audience. The project is being produced by the Art and Media Group at the Earth Observatory of Singapore, and it takes the shape of an e-book. It offers a consistent, comprehensive, and jargon-filtered synthesis of the main volcanic-risk related topics about Merapi: volcanic mechanisms, eruptive history, associated hazards and risks, the way inhabitants and scientists deal with it, and what daily life at Merapi looks like. The project provides a background to better understand volcanoes, and it points out some interactions between scientists and society. We propose two levels of interpretation: one that is understandable by 10-year old kids and above and an expert level with deeper presentations of specific topics. Thus, the Merapi Interactive project intends to provide an engaging and comprehensive interactive book that should interest kids, adults, as well as Earth Sciences undergraduates and academics. Merapi Interactive is scheduled for delivery in mid-2016.

  17. Catalog of earthquake hypocenters for Augustine, Redoubt, Iliamna, and Mount Spurr volcanoes, Alaska: January 1, 1991 - December 31, 1993

    Science.gov (United States)

    Jolly, Arthur D.; Power, John A.; Stihler, Scott D.; Rao, Lalitha N.; Davidson, Gail; Paskievitch, John F.; Estes, Steve; Lahr, John C.

    1996-01-01

    The Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, the Geophysical Institute of the University of Alaska, Fairbanks, and the Alaska Division of Geological and Geophysical Surveys, has maintained a program of seismic monitoring at potentially active volcanoes in the Cook Inlet region since 1988. The principal objectives of this program include the seismic surveillance of the Cook Inlet volcanoes and the investigation of seismic processes associated with active volcanism. This catalog reflects the status and evolution of the seismic monitoring program, and presents the basic seismic data for the time interval January 1, 1991, to December 31, 1993. For an interpretation of these data the reader should refer to several recent articles on volcano related seismicity in the Cook Inlet region (e.g. Jolly and others, 1994; Power and others, 1995; and McNutt and others, 1995). A similar catalog covers the period from October 12, 1989 to December 31, 1991 (Power and others 1993).

  18. OPTICON and the Virtual Observatory

    CERN Document Server

    Gilmore, G

    2000-01-01

    The challenges of multi-wavelength astrophysics require new outlooks from those appropriate to traditional astronomy. The next generation of research scientists must be trained to exploit the potentiality now being provided for the first time. Just as importantly, the full range of available information must be indexed and made available, to avoid wasteful repeat observations, or incomplete analyses. Perhaps the greatest challenge in the immediate future is to ensure the wealth of multi-wavelength data already available, and being accumulated, is available for efficient scientific exploitation. The difference between observations in a depositary and a fully-operational data archive is the difference between waste and cutting-edge science. The EU Optical Infrared Coordination Network for Astronomy (OPTICON) provides a forum to coordinate and develop the many national and international efforts and desires leading towards an operational virtial observatory.

  19. Autonomous Infrastructure for Observatory Operations

    Science.gov (United States)

    Seaman, R.

    This is an era of rapid change from ancient human-mediated modes of astronomical practice to a vision of ever larger time domain surveys, ever bigger "big data", to increasing numbers of robotic telescopes and astronomical automation on every mountaintop. Over the past decades, facets of a new autonomous astronomical toolkit have been prototyped and deployed in support of numerous space missions. Remote and queue observing modes have gained significant market share on the ground. Archives and data-mining are becoming ubiquitous; astroinformatic techniques and virtual observatory standards and protocols are areas of active development. Astronomers and engineers, planetary and solar scientists, and researchers from communities as diverse as particle physics and exobiology are collaborating on a vast range of "multi-messenger" science. What then is missing?

  20. IAXO - The International Axion Observatory

    CERN Document Server

    Vogel, J K; Cantatore, G.; Carmona, J.M.; Caspi, S.; Cetin, S.A.; Christensen, F.E.; Dael, A.; Dafni, T.; Davenport, M.; Derbin, A.V.; Desch, K.; Diago, A.; Dudarev, A.; Eleftheriadis, C.; Fanourakis, G.; Ferrer-Ribas, E.; Galan, J.; Garcia, J.A.; Garza, J.G.; Geralis, T.; Gimeno, B.; Giomataris, I.; Gninenko, S.; Gomez, H.; Hailey, C.J.; Hiramatsu, T.; Hoffmann, D.H.H.; Iguaz, F.J.; Irastorza, I.G.; Isern, J.; Jaeckel, J.; Jakovcic, K.; Kaminski, J.; Kawasaki, M.; Krcmar, M.; Krieger, C.; Lakic, B.; Lindner, A.; Liolios, A.; Luzon, G.; Ortega, I.; Papaevangelou, T.; Pivovaroff, M.J.; Raffelt, G.; Redondo, J.; Ringwald, A.; Russenschuck, S.; Ruz, J.; Saikawa, K.; Savvidis, I.; Sekiguchi, T.; Shilon, I.; Silva, H.; ten Kate, H.H.J.; Tomas, A.; Troitsky, S.; van Bibber, K.; Vedrine, P.; Villar, J.A.; Walckiers, L.; Wester, W.; Yildiz, S.C.; Zioutas, K.

    2013-01-01

    The International Axion Observatory (IAXO) is a next generation axion helioscope aiming at a sensitivity to the axion-photon coupling of a few 10^{-12} GeV^{-1}, i.e. 1-1.5 orders of magnitude beyond sensitivities achieved by the currently most sensitive axion helioscope, the CERN Axion Solar Telescope (CAST). Crucial factors in improving the sensitivity for IAXO are the increase of the magnetic field volume together with the extensive use of x-ray focusing optics and low background detectors, innovations already successfully tested at CAST. Electron-coupled axions invoked to explain the white dwarf cooling, relic axions, and a large variety of more generic axion-like particles (ALPs) along with other novel excitations at the low-energy frontier of elementary particle physics could provide additional physics motivation for IAXO.

  1. National Astronomical Observatory of Japan

    CERN Document Server

    Haubold, Hans J; UN/ESA/NASA Workshop on the International Heliophysical Year 2007 and Basic Space Science, hosted by the National Astronomical Observatory of Japan

    2010-01-01

    This book represents Volume II of the Proceedings of the UN/ESA/NASA Workshop on the International Heliophysical Year 2007 and Basic Space Science, hosted by the National Astronomical Observatory of Japan, Tokyo, 18 - 22 June, 2007. It covers two programme topics explored in this and past workshops of this nature: (i) non-extensive statistical mechanics as applicable to astrophysics, addressing q-distribution, fractional reaction and diffusion, and the reaction coefficient, as well as the Mittag-Leffler function and (ii) the TRIPOD concept, developed for astronomical telescope facilities. The companion publication, Volume I of the proceedings of this workshop, is a special issue in the journal Earth, Moon, and Planets, Volume 104, Numbers 1-4, April 2009.

  2. Goddard Geophysical and Astronomical Observatory

    Science.gov (United States)

    Figueroa, Ricardo

    2013-01-01

    This report summarizes the technical parameters and the technical staff of the VLBI system at the fundamental station GGAO. It also gives an overview about the VLBI activities during the report year. The Goddard Geophysical and Astronomical Observatory (GGAO) consists of a 5-meter radio telescope for VLBI, a new 12-meter radio telescope for VLBI2010 development, a 1-meter reference antenna for microwave holography development, an SLR site that includes MOBLAS-7, the NGSLR development system, and a 48" telescope for developmental two-color Satellite Laser Ranging, a GPS timing and development lab, a DORIS system, meteorological sensors, and a hydrogen maser. In addition, we are a fiducial IGS site with several IGS/IGSX receivers. GGAO is located on the east coast of the United States in Maryland. It is approximately 15 miles NNE of Washington, D.C. in Greenbelt, Maryland.

  3. The Jiangmen Underground Neutrino Observatory

    CERN Document Server

    Grassi, Marco

    2016-01-01

    The Jiangmen Underground Neutrino Observatory (JUNO) is a large and high precision liquid scintillator detector under construction in the south of China. With its 20 kt target mass, it aims to achieve an unprecedented 3% energy resolution at 1 MeV. Its main goal is to study the disappearance of reactor antineutrino to determine the neutrino mass ordering, and to precisely measure the mixing parameters $\\theta_{12}$, $\\Delta m^2_{12}$, and $\\Delta m ^2_{ee}$. It also aims to detect neutrinos emitted from radioactive processes taking place within the inner layers of the Earth (geonutrinos), as well as neutrinos produced during rare supernova bursts. Neutrinos emitted in solar nuclear reactions could also be observed, if stringent radiopurity requirements on the scintillator are met. This manuscript provides some highlights of JUNO's Physics Programme, and describes the detector design, as well as the ongoing detector R&D.

  4. TUM Critical Zone Observatory, Germany

    Science.gov (United States)

    Völkel, Jörg; Eden, Marie

    2014-05-01

    Founded 2011 the TUM Critical Zone Observatory run by the Technische Universität München and partners abroad is the first CZO within Germany. TUM CZO is both, a scientific as well as an education project. It is a watershed based observatory, but moving behind this focus. In fact, two mountainous areas are integrated: (1) The Ammer Catchment area as an alpine and pre alpine research area in the northern limestone Alps and forelands south of Munich; (2) the Otter Creek Catchment in the Bavarian Forest with a crystalline setting (Granite, Gneiss) as a mid mountainous area near Regensburg; and partly the mountainous Bavarian Forest National Park. The Ammer Catchment is a high energy system as well as a sensitive climate system with past glacial elements. The lithology shows mostly carbonates from Tertiary and Mesozoic times (e.g. Flysch). Source-to-sink processes are characteristic for the Ammer Catchment down to the last glacial Ammer Lake as the regional erosion and deposition base. The consideration of distal depositional environments, the integration of upstream and downstream landscape effects are characteristic for the Ammer Catchment as well. Long term datasets exist in many regards. The Otter Creek catchment area is developed in a granitic environment, rich in saprolites. As a mid mountainous catchment the energy system is facing lower stage. Hence, it is ideal comparing both of them. Both TUM CZO Catchments: The selected catchments capture the depositional environment. Both catchment areas include historical impacts and rapid land use change. Crosscutting themes across both sites are inbuilt. Questions of ability to capture such gradients along climosequence, chronosequence, anthroposequence are essential.

  5. HELIO: A Heliospheric Virtual Observatory

    Science.gov (United States)

    Aboudarham, J.; Bentley, R. D.; Csillaghy, A.

    2012-09-01

    HELIO, the Heliophysics Integrated Observatory, is a Research Infrastructure funded under EC's FP7 Capacities Specific Programme. It began in June 2009 for three years. It will provide the heliophysics research community with an integrated e-infrastructure that has no equivalent anywhere else. The project objectives are as follows: - to create a collaborative environment where scientists can discover, understand and model the connection between solar phenomena, interplanetary disturbances and their effects on the planets (esp. the Earth) - to establish a consensus on standards for describing all heliophysical data and champion them within international standards bodies, e.g. the IVOA - to develop new ways to interact with a virtual observatory that are more closely aligned with the way researchers wish to use the data. HELIO is based on a Service-Oriented architecture. For this purpose, HELIO developed a Front End, which facilitates the search for data, using series of search metadata services covering different domains (many Events and Features available; use of context information to refine selection); Services to identify and retrieve observations based on search results (knows which data are stored where and how to access them); Enabling services such as tools to find and track events/phenomena in 4D environment (i.e. including the propagation of phenomena). Services can be used individually or combined through workflow capability. Heliophysics Event Catalogue and Heliophysics Features Catalogue provide a specific access to information concerning phenomena that occur in the Solar system. A semantic-driven approach is used to integrate data from different domains, based on ontology derived from existing data models. Thirteen partners from Europe and US are involved in this project. And although it is not completed, a prototype is already available, which can be accessed through HELIO web site (http://www.helio-vo.eu/).

  6. Highlights from the High Altitude Water Cherenkov Observatory

    CERN Document Server

    Pretz, John

    2015-01-01

    The High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory was completed this year at a 4100-meter site on the flank of the Sierra Negra volcano in Mexico. HAWC is a water Cherenkov ground array with the capability to distinguish 100 GeV - 100 TeV gamma rays from the hadronic cosmic-ray background. HAWC is uniquely suited to study extremely high energy cosmic-ray sources, search for regions of extended gamma-ray emission, and to identify transient gamma-ray phenomena. HAWC will play a key role in triggering multi-wavelength and multi-messenger studies of active galaxies, gamma-ray bursts, supernova remnants and pulsar wind nebulae. Observation of TeV photons also provide unique tests for a number of fundamental physics phenomena including dark matter annihilation and primordial black hole evaporation. Operation began mid-2013 with the partially-completed detector. Multi-TeV emission from the Galactic Plane is clearly seen in the first year of operation, confirming a number of known TeV sources, and a numb...

  7. Three-axial Fiber Bragg Grating Strain Sensor for Volcano Monitoring

    Science.gov (United States)

    Giacomelli, Umberto; Beverini, Nicolò; Carbone, Daniele; Carelli, Giorgio; Francesconi, Francesco; Gambino, Salvatore; Maccioni, Enrico; Morganti, Mauro; Orazi, Massimo; Peluso, Rosario; Sorrentino, Fiodor

    2017-04-01

    Fiber optic and FBGs sensors have attained a large diffusion in the last years as cost-effective monitoring and diagnostic devices in civil engineering. However, in spite of their potential impact, these instruments have found very limited application in geophysics. In order to study earthquakes and volcanoes, the measurement of crustal deformation is of crucial importance. Stress and strain behaviour is among the best indicators of changes in the activity of volcanoes .. Deep bore-hole dilatometers and strainmeters have been employed for volcano monitoring. These instruments are very sensitive and reliable, but are not cost-effective and their installation requires a large effort. Fiber optic based devices offer low cost, small size, wide frequency band, easier deployment and even the possibility of creating a local network with several sensors linked in an array. We present the realization, installation and first results of a shallow-borehole (8,5 meters depth) three-axial Fiber Bragg Grating (FBG) strain sensor prototype. This sensor has been developed in the framework of the MED-SUV project and installed on Etna volcano, in the facilities of the Serra La Nave astrophysical observatory. The installation siteis about 7 Km South-West of the summit craters, at an elevation of about 1740 m. The main goal of our work is the realization of a three-axial device having a high resolution and accuracy in static and dynamic strain measurements, with special attention to the trade-off among resolution, cost and power consumption. The sensor structure and its read-out system are innovative and offer practical advantages in comparison with traditional strain meters. Here we present data collected during the first five months of operation. In particular, the very clear signals recorded in the occurrence of the Central Italy seismic event of October 30th demonstrate the performances of our device.

  8. Integrating SAR and derived products into operational volcano monitoring and decision support systems

    Science.gov (United States)

    Meyer, F. J.; McAlpin, D. B.; Gong, W.; Ajadi, O.; Arko, S.; Webley, P. W.; Dehn, J.

    2015-02-01

    Remote sensing plays a critical role in operational volcano monitoring due to the often remote locations of volcanic systems and the large spatial extent of potential eruption pre-cursor signals. Despite the all-weather capabilities of radar remote sensing and its high performance in monitoring of change, the contribution of radar data to operational monitoring activities has been limited in the past. This is largely due to: (1) the high costs associated with radar data; (2) traditionally slow data processing and delivery procedures; and (3) the limited temporal sampling provided by spaceborne radars. With this paper, we present new data processing and data integration techniques that mitigate some of these limitations and allow for a meaningful integration of radar data into operational volcano monitoring decision support systems. Specifically, we present fast data access procedures as well as new approaches to multi-track processing that improve near real-time data access and temporal sampling of volcanic systems with SAR data. We introduce phase-based (coherent) and amplitude-based (incoherent) change detection procedures that are able to extract dense time series of hazard information from these data. For a demonstration, we present an integration of our processing system with an operational volcano monitoring system that was developed for use by the Alaska Volcano Observatory (AVO). Through an application to a historic eruption, we show that the integration of SAR into systems such as AVO can significantly improve the ability of operational systems to detect eruptive precursors. Therefore, the developed technology is expected to improve operational hazard detection, alerting, and management capabilities.

  9. Sensibility analysis of VORIS lava-flow simulations: application to Nyamulagira volcano, Democratic Republic of Congo

    Directory of Open Access Journals (Sweden)

    A. M. Syavulisembo

    2015-03-01

    Full Text Available Assessment and management of volcanic risk are important scientific, economic, and political issues, especially in densely populated areas threatened by volcanoes. The Virunga area in the Democratic Republic of Congo, with over 1 million inhabitants, has to cope permanently with the threat posed by the active Nyamulagira and Nyiragongo volcanoes. During the past century, Nyamulagira erupted at intervals of 1–4 years – mostly in the form of lava flows – at least 30 times. Its summit and flank eruptions lasted for periods of a few days up to more than two years, and produced lava flows sometimes reaching distances of over 20 km from the volcano, thereby affecting very large areas and having a serious impact on the region of Virunga. In order to identify a useful tool for lava flow hazard assessment at the Goma Volcano Observatory (GVO, we tested VORIS 2.0.1 (Felpeto et al., 2007, a freely available software (http://www.gvb-csic.es based on a probabilistic model that considers topography as the main parameter controlling lava flow propagation. We tested different Digital Elevation Models (DEM – SRTM1, SRTM3, and ASTER GDEM – to analyze the sensibility of the input parameters of VORIS 2.0.1 in simulation of recent historical lava-flow for which the pre-eruption topography is known. The results obtained show that VORIS 2.0.1 is a quick, easy-to-use tool for simulating lava-flow eruptions and replicates to a high degree of accuracy the eruptions tested. In practice, these results will be used by GVO to calibrate VORIS model for lava flow path forecasting during new eruptions, hence contributing to a better volcanic crisis management.

  10. WIMPs search at OTO Cosmo Observatory

    Science.gov (United States)

    Fushimi, K.; Ichihara, K.; Koori, N.; Nakayama, S.; Shichijo, Y.; Ogawa, I.; Yoshida, S.; Ajimura, S.; Hazama, R.; Ishikawa, Y.; Itamura, M.; Kishimoto, T.; Kunitomi, G.; Matsuoka, K.; Miyawaki, H.; Shiomi, S.; Suzuki, N.; Tanaka, Y.; Umehara, S.; Ejiri, H.; Kudomi, N.; Kume, K.; Takahisa, K.; Ohsumi, H.; Yanagida, Y.

    2003-03-01

    WIMPs dark matter and double beta decays has been studied at OTO Cosmo Observatory. The observatory has great advantages of small cosmic ray flux, small neutron flux and small radon density. The recent status of WIMPs search by huge NaI (ELEGANT V), large CaF2Eu) (ELEGANT VI) and high sesitive NaI detector are reported.

  11. HAWC observatory catches first gamma rays

    Science.gov (United States)

    Frías Villegas, Gabriela

    2013-06-01

    The world's largest and most modern gamma-ray observatory has carried out its first successful observations. Located inside the Pico de Orizaba national park in the Mexican state of Puebla, the High-Altitude Water Cherenkov Observatory (HAWC) is a collaboration between 26 Mexican and US institutions.

  12. Highlights from the Pierre Auger Observatory

    NARCIS (Netherlands)

    Letessier-Selvon, Antoine; for the Pierre Auger Collaboration, [No Value; :, [No Value; Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muniz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antivcic, T.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bardenet, R.; Baeuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Belletoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blumer, H.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Burton, R. E.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Diaz, J. C.; Diaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipcic, A.; Foerster, N.; Fox, B. D.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Frohlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; Garcia, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giller, M.; Gitto, J.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gomez Berisso, M.; Gomez Vitale, P. F.; Goncalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Homola, P.; Hoerandel, J. R.; Horvath, P.; Hrabovsky, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kadija, K.; Kambeitz, O.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kegl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp d, J.; Krause, R.; Krohm, N.; Kroemer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leao, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Lhenry-Yvon, I.; Link, K.; Lopez, R.; Lopez Aguera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martinez, H.; Martinez Bravo, O.; Martraire, D.; Masias Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Micanovic, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Mostafa, M.; Moura, C. A.; Muller, M. A.; Muller, G.; Munchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novzka, L.; Oehlschlager, J.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Pekala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Pontz, M.; Porcelli, A.; Preda, T.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Frias, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouille-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Ruhle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sanchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovanek, P.; Schroeder, F. G.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Smialkowski, A.; Smida, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanic, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Straub, M.; Stutz, A.; Suarez, F.; Suomijarvi, T.; Supanitsky, A. D.; Susa, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Tacscuau, O.; Tcaciuc, R.; Thao, N. T.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tome, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Tridapalli, D. B.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Valdes Galicia, J. F.; Valino, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cardenas, B.; Varner, G.; Vazquez, J. R.; Vazquez, R. A.; Veberic, D.; Verzi, V.; Vicha, J.; Videla, M.; Villasenor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczynska, B.; Wilczynski, H.; Will, M.; Williams, C.; Winchen, T.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Martin, L.

    2013-01-01

    The Pierre Auger Observatory is the world's largest cosmic ray observatory. Our current exposure reaches nearly 40,000 km$^2$ str and provides us with an unprecedented quality data set. The performance and stability of the detectors and their enhancements are described. Data analyses have led to a n

  13. Global Health Observatory (GHO): Life Expectancy

    Science.gov (United States)

    ... WHO Language عربي 中文 English Français Русский Español Global Health Observatory (GHO) data Menu Global Health Observatory ... years on average in 2015 MORE MORTALITY AND GLOBAL HEALTH ESTIMATES DATA PRODUCTS Maps Country profiles About ...

  14. Highlights from the Pierre Auger Observatory

    NARCIS (Netherlands)

    Letessier-Selvon, Antoine; for the Pierre Auger Collaboration, [No Value; :, [No Value; Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muniz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antivcic, T.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bardenet, R.; Baeuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Belletoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blumer, H.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Burton, R. E.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Diaz, J. C.; Diaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipcic, A.; Foerster, N.; Fox, B. D.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Frohlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; Garcia, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giller, M.; Gitto, J.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gomez Berisso, M.; Gomez Vitale, P. F.; Goncalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Homola, P.; Hoerandel, J. R.; Horvath, P.; Hrabovsky, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kadija, K.; Kambeitz, O.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kegl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp d, J.; Krause, R.; Krohm, N.; Kroemer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leao, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Lhenry-Yvon, I.; Link, K.; Lopez, R.; Lopez Aguera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martinez, H.; Martinez Bravo, O.; Martraire, D.; Masias Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Micanovic, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Mostafa, M.; Moura, C. A.; Muller, M. A.; Muller, G.; Munchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novzka, L.; Oehlschlager, J.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Pekala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Pontz, M.; Porcelli, A.; Preda, T.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Frias, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouille-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Ruhle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sanchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovanek, P.; Schroeder, F. G.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Smialkowski, A.; Smida, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanic, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Straub, M.; Stutz, A.; Suarez, F.; Suomijarvi, T.; Supanitsky, A. D.; Susa, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Tacscuau, O.; Tcaciuc, R.; Thao, N. T.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tome, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Tridapalli, D. B.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Valdes Galicia, J. F.; Valino, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cardenas, B.; Varner, G.; Vazquez, J. R.; Vazquez, R. A.; Veberic, D.; Verzi, V.; Vicha, J.; Videla, M.; Villasenor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczynska, B.; Wilczynski, H.; Will, M.; Williams, C.; Winchen, T.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Martin, L.

    2013-01-01

    The Pierre Auger Observatory is the world's largest cosmic ray observatory. Our current exposure reaches nearly 40,000 km$^2$ str and provides us with an unprecedented quality data set. The performance and stability of the detectors and their enhancements are described. Data analyses have led to a n

  15. Propriétés Electroniques du YVO3, CaVO3 Et Leur Composé Y1-XCaxVO3

    OpenAIRE

    TRARI, Djamel

    2010-01-01

    Dans ce mémoire de magister nous avons étudié deux composés : le YVO3, un isolant de Mott et le CaVO3, conducteur métallique théoriquement. Nous avons effectué des simulations par des méthodes ab-initio se basant sur la théorie de la fonctionnelle de densité, en l’occurrence les deux méthodes de calcul : FP-LAPW et les pseudopotentiels quantiques incorporée dans les code Wien2k et VASP respectivement. Contrairement à d’autres références bibliographiques nous avons trouvé que le...

  16. A low-threshold efficient KTA OPO by a fiber-coupled diode-end-pumped Nd:YVO4 laser

    Institute of Scientific and Technical Information of China (English)

    ZHONG Kai; YAO Jian-quan; XU De-gang; WANG Yu-ye; WANG Peng

    2010-01-01

    @@ A low-threshold efficient high-repetition-rate eye-safe optical parametric oscillator (OPO) is presented. The OPO is based on an x-cut non-critically phase-matched (NCPM) KTA intra-cavity pumped by an acousto-optieally (A-O) Q-switched Nd:YVO4 laser. At 10 kHz, the lowest threshold of 0.75 W and the signal power of 0.6 W are got, corresponding to the single pulse energy of 60 μJ and the peak power of 20 kW. Tuning the frequency, the maximum output power at 1536 nm is 1.03 W at 30 kHz with an optical-to-optical conversion efficiency of 12.26%. The fluctuation of the output power is 2.1%during 2 h operation.

  17. Violet to Infrared Multiwavelength Generation in Periodically Poled Lithium Niobate Pumped by a Q-Switched Nd:YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    许祖彦; 梁晓燕; 李健; 姚爱云; 林学春; 崔大复; 吴令安

    2002-01-01

    Six output wavelengths from violet to infrared have been observed simultaneously from an all-solid-state laser pumped optical parametric oscillator in a periodically poled lithium niobate crystal. The output wavelengths can be tuned by varying the quasi-phase matched period and/or temperature. The pump laser is a diode-pumped passive Q-switched Nd:YVO4 laser operated at 1064nm. Using a crystal with a 29.9μm grating period, we measured six wavelengths at 448, 515, 532, 630, 773 and 1546nm and obtained efficient output. We explain the multiwavelength generation by multiwave coupling theory. This phenomenon may have novel applications in photonic devices.

  18. Diode array pumped, non-linear mirror Q-switched and mode-locked Nd : YVO4 laser – a good tool for powder SHG measurement

    Indian Academy of Sciences (India)

    P K Datta; Chandrajit Basu; S Mukhopadhyay; S K Das; G K Samanta; Antonio Agnesi

    2004-11-01

    A non-linear mirror consisting of a lithium triborate crystal and a dichroic output coupler are used to mode-lock (passively) an Nd : YVO4 laser, pumped by a diode laser array. The laser can operate both in cw mode-locked and simultaneously Q-switched and mode-locked (QML) regime. The peak power of the laser while operating in QML regime is much higher but pulses suffers from poor amplitude stability. The incorporation of an acousto-optic modulator as an active Q-switch enhances the stability of the QML pulse envelope. The second-order non-linearity of powdered crystalline urea is conclusively measured with respect to KDP while the laser is operating in passively Q-switched and passively mode-locked regime as well as in actively Q-switched and passively mode-locked regime.

  19. 10 kHz ps 1342 nm laser generation by an electro-optically cavity-dumped mode-locked Nd:YVO4 laser

    Science.gov (United States)

    Chen, Ying; Liu, Ke; He, Li-jiao; Yang, Jing; Zong, Nan; Yang, Feng; Gao, Hong-wei; Liu, Zhao; Yuan, Lei; Lan, Ying-jie; Bo, Yong; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

    2017-01-01

    We have demonstrated an electro-optically cavity-dumped mode-locked (CDML) picosecond Nd:YVO4 laser at 1342 nm with 880 nm diode-laser direct pumping. At a repetition rate of 10 kHz, an average output power of 0.119 W was achieved, corresponding to a pulse energy of 11.9 μJ. Compared with the continuous wave mode-locking pulse energy of 17.5 nJ, the CDML pulse energy was 680 times higher. The pulse width was measured to be 33.4 ps, resulting in the peak power of 356 kW. Meanwhile, the beam quality was nearly diffraction limited with an average beam quality factor M2 of 1.29.

  20. Efficient and high-power laser-diode single-end-pumped Nd:YVO4 continuous wave laser at 1342 nm

    Institute of Scientific and Technical Information of China (English)

    Zhang Yu-Ping; Zheng Yi; Zhang Hui-Yun; Wang Peng; Yao Jian-Quan

    2006-01-01

    A compact, efficient and high-power laser diode (LD) single-end-pumped Nd:YVO4 laser with continuous-wave emission at 1342 nm is reported. With a single crystal single-end-pumped by fibre-coupled LD array, an output power of 7.36W is obtained from the laser cavity of concave-convex shape, corresponding to an optical-to-optical efficiency of 32.8%. The laser is operated in TEM00 mode with small rms amplitude noise of 0.3%. The influences of the Nd concentration, transmissivity of the output mirror and the cavity length on the output power have been studied experimentally.

  1. Cr4+:YAG passively Q-switched c-cut Nd:YVO4 self-Raman laser at 1168.6 nm

    Science.gov (United States)

    Lin, H. Y.; Pan, X.; Huang, X. H.; Xiao, M.; Xu, Y. C.; Zhu, W. Z.

    2016-03-01

    We demonstrate the first Cr4+:YAG passively Q-switched c-cut Nd:YVO4 self-Raman laser at 1168.6 nm based on the Stokes shift of 816 cm-1. At the pump power of 4.7 W, the maximum output power of the Stokes line at 1168.6 nm is 270.5 mW, corresponding to an optical conversion efficiency of 5.8%. The pulse width, pulse repetition rate, pulse energy and peak power are 8.8 ns, 35.8 kHz, 7.6 μJ and 0.86 kW, respectively. At the pump of 5.0 W, the Stokes line at 1097.2 nm based on Raman shift of 259 cm-1 also appears.

  2. 1 400-1 500 nm,Different Material-doped Raman Fiber Lasers Pumped by Nd∶YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    MEI Jin-jie; LIU De-ming; WANG Ying; HUANG De-xiu

    2003-01-01

    Different material-doped Raman fiber lasers with very high efficiency operating in continuous-wave are presented.With 1 W Nd∶YVO4 laser pumping at wavelength of 1 342 nm,single mode output power of above 500 mW (optical-to-optical conversion efficiency of 50%) is simulated in the range of 1 400-1 500 nm.Using high-germanium,high-phosphate and high-borate silicate fibers as the gain medium,laser output at wavelengths of 1 420,1 450,1 480 and 1 495 nm can be achieved with different geometries,which are just as pumping C-band and L-band distributed Raman fiber amplifiers.

  3. Simultaneous Q-switching and Frequency-doubling by a Single KTP Crystal in a Diode-pumped Nd: YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; HUO Yujing; HE Shufang; FENG Lichun

    2000-01-01

    The interrelation between the phase matching condition for second harmonic generation (SHG) and the electro-optic Q-switching in KTP was numerically analyzed. A diode-pumped Q-switched Nd: YVO4/KTP green laser was reported, where the KTP crystal was simultaneously used as both an electrooptic Q-switcher and a frequency-doubling crystal in type Ⅱ phase matching.Compared with the conventional frequency-doubling and Q-switching configuration, low loss and high efficiency characteristics were realized by using a single KTP crystal. The Q-switched green laser pulse with a peak power of 762 W and a pulse width of 12 ns was obtained with 1 W pump power.

  4. Generation of UV radiation at 335.5 nm based on frequency-quadrupling of a diode-pumped Nd:YVO4 laser

    Institute of Scientific and Technical Information of China (English)

    Xiuwei Fan; Haitao Huang; Jijian Jiang; Jingliang He

    2008-01-01

    The generation of ultraviolet(UV)light at 335.5 nm based on frequency quadrupling of a diode-endpumped Q-switched Nd:YVO4 laser at 1342 nm was demonstrated.KTP crystal was used for generation of wavelength of 671 nm by intracavity doubling and LBO (BBO) crystal Was exploited for the subsequent external fourth harmonic generation(FHG).With 6.3-W absorbed pump power and 10-kHz frequency repetition rate,the UV output power of 35 and 63 mW were obtained by using LBO and BBO as frequency quadrupling nonlinear crystals, respectively. The experimenta results show that the conversion efficiency (red-UV)of 6.4% for BBO crystal is higher than that of 3.5% for LB0 crystal, but the UV beam quality obtained by LBO crystal is better than by BBO crystal.

  5. Spatial dynamic thermal iteration model for 888 nm end-pumped Nd:YVO4 solid-state laser oscillators and amplifiers

    Science.gov (United States)

    Shen, Yijie; Gong, Mali; Ji, Encai; Fu, Xing; Sun, Licheng

    2017-01-01

    A new theoretical model, spatial dynamic thermal iteration (SDTI) model, for diode-end-pumped solid-state laser systems is developed, which is both applicable to laser oscillators and amplifiers. The influences of pump beam quality, ground state absorption and depletion (GSA/GSD) and energy transfer upconversion (ETU) are included in our model. According to the basic principles of nonradiative transitions and population dynamics, we can obtain the spatial distribution of heat generation and temperature within the laser crystal through numerically solving heat conduction equation by finite element method (FEM). Furthermore, a spatial mesh iteration algorithm is designed to analyze the temperature dependence of absorption cross section, emission cross section and thermal conductivity. Finally, the simulated results of our SDTI model was proved to precisely coincide with the reported experimental results in classical 888 nm end-pumped Nd:YVO4 laser oscillator and amplifier systems.

  6. Seismic unrest at Katla Volcano- southern Iceland

    Science.gov (United States)

    jeddi, zeinab; Tryggvason, Ari; Gudmundsson, Olafur; Bödvarsson, Reynir; SIL Seismology Group

    2014-05-01

    Katla volcano is located on the propagating Eastern Volcanic Zone (EVZ) in South Iceland. It is located beneath Mýrdalsjökull ice-cap which covers an area of almost 600 km2, comprising the summit caldera and the eruption vents. 20 eruptions between 930 and 1918 with intervals of 13-95 years are documented at Katla which is one of the most active subglacial volcanoes in Iceland. Eruptions at Katla are mainly explosive due to the subglacial mode of extrusion and produce high eruption columns and catastrophic melt water floods (jökulhlaups). The present long Volcanic repose (almost 96 years) at Katla, the general unrest since 1955, and the 2010 eruption of the neighbouring Eyjafjallajökull volcano has prompted concerns among geoscientists about an imminent eruption. Thus, the volcano has been densely monitored by seismologists and volcanologists. The seismology group of Uppsala University as a partner in the Volcano Anatomy (VA) project in collaboration with the University of Iceland and the Icelandic Meteorological Office (IMO) installed 9 temporary seismic stations on and around the Mýrdalsjökull glacier in 2011. Another 10 permanent seismic stations are operated by IMO around Katla. The project's data collection is now finished and temporary stations were pulled down in August 2013. According to seismicity maps of the whole recording period, thousands of microearthquakes have occurred within the caldera region. At least three different source areas are active in Katla: the caldera region, the western Godaland region and a small cluster at the southern rim of Mýrdalsjökull near the glacial stream of Hafursarjökull. Seismicity in the southern flank has basically started after June 2011. The caldera events are mainly volcano-tectonic, while western and southern events are mostly long period (lp) and can be related to glacial or magmatic movement. One motivation of the VA Katla project is to better understand the physical mechanism of these lp events. Changes

  7. The Pierre Auger Cosmic Ray Observatory

    CERN Document Server

    ,

    2015-01-01

    The Pierre Auger Observatory, located on a vast, high plain in western Argentina, is the world's largest cosmic ray observatory. The objectives of the Observatory are to probe the origin and characteristics of cosmic rays above $10^{17}$ eV and to study the interactions of these, the most energetic particles observed in nature. The Auger design features an array of 1660 water-Cherenkov particle detector stations spread over 3000 km$^2$ overlooked by 24 air fluorescence telescopes. In addition, three high elevation fluorescence telescopes overlook a 23.5 km$^2$, 61 detector infill array. The Observatory has been in successful operation since completion in 2008 and has recorded data from an exposure exceeding 40,000 km$^2$ sr yr. This paper describes the design and performance of the detectors, related subsystems and infrastructure that make up the Auger Observatory.

  8. The Pierre Auger Cosmic Ray Observatory

    Science.gov (United States)

    Pierre Auger Collaboration

    2015-10-01

    The Pierre Auger Observatory, located on a vast, high plain in western Argentina, is the world's largest cosmic ray observatory. The objectives of the Observatory are to probe the origin and characteristics of cosmic rays above 1017 eV and to study the interactions of these, the most energetic particles observed in nature. The Auger design features an array of 1660 water Cherenkov particle detector stations spread over 3000 km2 overlooked by 24 air fluorescence telescopes. In addition, three high elevation fluorescence telescopes overlook a 23.5 km2, 61-detector infilled array with 750 m spacing. The Observatory has been in successful operation since completion in 2008 and has recorded data from an exposure exceeding 40,000 km2 sr yr. This paper describes the design and performance of the detectors, related subsystems and infrastructure that make up the Observatory.

  9. A 200 kHz Q-Switched Adhesive-Free Bond Composite Nd:YVO4 Laser using a Double-Crystal RTP Electro-optic Modulator

    Institute of Scientific and Technical Information of China (English)

    YU Yong-Ji; CHEN Xin-Yu; WANG Chao; WU Chun-Ting; LIU Rui; JIN Guang-Yong

    2012-01-01

    A diode-end-pumped electro-optic (EO) Q-switched adhesive-free bond composite Nd:YVO4 laser operating at a repetition rate of 200 kHz is reported. A pair of RbTiOPOi (RTP) crystals are used as a high repetition EO Q-switch. At the repetition rate of 200kHz, the maximum average output power of 11.8 W at wavelength 1064 nm and full width at half maximum of pulses of 16.65 ns are achieved at an incident pump power of 27 W, corresponding to an optical conversion efficiency of 43.7% and a slope efficiency of 44.6%, respectively. To the best of our knowledge, this is the highest repetition rate reported on the EO Q-switched laser by using RTP crystals.%A diode-end-pumped electro-optic (EO) Q-switched adhesive-free bond composite Nd:YVO4 laser operating at a repetition rate of 200 kHz is reported.A pair of RbTiOPO4 (RTP) crystals are used as a high repetition EO Q-switch.At the repetition rate of 200kHz,the maximum average output power of 11.8 W at wavelength 1064 nm and full width at half maximum of pulses of 16.65ns are achieved at an incident pump power of 27 W,corresponding to an optical conversion efficiency of 43.7% and a slope efficiency of 44.6%,respectively.To the best of our knowledge,this is the highest repetition rate reported on the EO Q-switched laser by using RTP crystals.

  10. Volcanoes in the Classroom--an Explosive Learning Experience.

    Science.gov (United States)

    Thompson, Susan A.; Thompson, Keith S.

    1996-01-01

    Presents a unit on volcanoes for third- and fourth-grade students. Includes demonstrations; video presentations; building a volcano model; and inviting a scientist, preferably a vulcanologist, to share his or her expertise with students. (JRH)

  11. Volcanostratigraphic Approach for Evaluation of Geothermal Potential in Galunggung Volcano

    Science.gov (United States)

    Ramadhan, Q. S.; Sianipar, J. Y.; Pratopo, A. K.

    2016-09-01

    he geothermal systems in Indonesia are primarily associated with volcanoes. There are over 100 volcanoes located on Sumatra, Java, and in the eastern part of Indonesia. Volcanostratigraphy is one of the methods that is used in the early stage for the exploration of volcanic geothermal system to identify the characteristics of the volcano. The stratigraphy of Galunggung Volcano is identified based on 1:100.000 scale topographic map of Tasikmalaya sheet, 1:50.000 scale topographic map and also geological map. The schematic flowchart for evaluation of geothermal exploration is used to interpret and evaluate geothermal potential in volcanic regions. Volcanostratigraphy study has been done on Galunggung Volcano and Talaga Bodas Volcano, West Java, Indonesia. Based on the interpretation of topographic map and analysis of the dimension, rock composition, age and stress regime, we conclude that both Galunggung Volcano and Talaga Bodas Volcano have a geothermal resource potential that deserve further investigation.

  12. USGS U.S. Volcanoes with Elevated Status

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Website provides list of elevated status volcanoes with access to activity updates and/or information releases for changes in activity at the volcanoes. activity at...

  13. International lunar observatory / power station: from Hawaii to the Moon

    Science.gov (United States)

    Durst, S.

    -like lava flow geology adds to Mauna Kea / Moon similarities. Operating amidst the extinct volcano's fine grain lava and dust particles offers experience for major challenges posed by silicon-edged, powdery, deep and abundant lunar regolith. Power stations for lunar observatories, both robotic and low cost at first, are an immediate enabling necessity and will serve as a commercial-industrial driver for a wide range of lunar base technologies. Both microwave rectenna-transmitters and radio-optical telescopes, maybe 1-meter diameter, can be designed using the same, new ultra-lightweight materials. Five of the world's six major spacefaring powers - America, Russia, Japan, China and India, are located around Hawaii in the Pacific / Asia area. With Europe, which has many resources in the Pacific hemisphere including Arianespace offices in Tokyo and Singapore, they have 55-60% of the global population. New international business partnerships such as Sea Launch in the mid-Pacific, and national ventures like China's Hainan spaceport, Japan's Kiribati shuttle landing site, Australia and Indonesia's emerging launch sites, and Russia's Ekranoplane sea launcher / lander - all combine with still more and advancing technologies to provide the central Pacific a globally representative, state-of-the-art and profitable access to space in this new century. The astronomer / engineers tasked with operation of the lunar observatory / power station will be the first to voyage from Hawaii to the Moon, before this decade is out. Their scientific and technical training at the world's leading astronomical complex on the lunar-like landscape of Mauna Kea may be enhanced with the learning and transmission of local cultures. Following the astronomer / engineers, tourism and travel in the commercially and technologically dynamic Pacific hemisphere will open the new ocean of space to public access in the 21st century like they opened the old ocean of sea and air to Hawaii in the 20th - with Hawaii

  14. Observed inflation-deflation cycles at Popocatepetl volcano using tiltmeters and its possible correlation with regional seismic activity in Mexico

    Science.gov (United States)

    Contreras Ruiz Esparza, M. G., Sr.; Jimenez Velazquez, J. C., Sr.; Valdes Gonzalez, C. M., Sr.; Reyes Pimentel, T. A.; Galaviz Alonso, S. A.

    2014-12-01

    Popocatepetl, the smoking mountain, is a stratovolcano located in central Mexico with an elevation of 5450 masl. The active volcano, close to some of the largest urban centers in Mexico - 60 km and 30 km far from Mexico City and Puebla, respectively - poses a high hazard to an estimated population of 500 thousand people living in the vicinity of the edifice. Accordingly, in July 1994 the Popocatepetl Volcanological Observatory (POVO) was established. The observatory is operated and supported by the National Center for Disaster Prevention of Mexico (CENAPRED), and is equipped to fully monitor different aspects of the volcanic activity. Among the instruments deployed, we use in this investigation two tiltmometers and broad-band seismometers at two sites (Chipiquixtle and Encinos), which send the information gathered continuously to Mexico City.In this research, we study the characteristics of the tiltmeters signals minutes after the occurrence of certain earthquakes. The Popocatepetl volcano starts inflation-deflation cycles due to the ground motion generated by events located at certain regions. We present the analysis of the tiltmeters and seismic signals of all the earthquakes (Mw>5) occurred from January 2013 to June 2014, recorded at Chipiquixtle and Encinos stations. First, we measured the maximum tilt variation after each earthquake. Next, we apply a band-pass filter for different frequency ranges to the seismic signals of the two seismic stations, and estimated the total energy of the strong motion phase of the seismic record. Finally, we compared both measurements and observed that the maximum tilt variations were occurring when the maximum total energy of the seismic signals were in a specific frequency range. We also observed that the earthquake records that have the maximum total energy in that frequency range were the ones with a epicentral location south-east of the volcano. We conclude that our observations can be used set the ground for an early

  15. The GEOSCOPE broadband seismic observatory

    Science.gov (United States)

    Douet, Vincent; Vallée, Martin; Zigone, Dimitri; Bonaimé, Sébastien; Stutzmann, Eléonore; Maggi, Alessia; Pardo, Constanza; Bernard, Armelle; Leroy, Nicolas; Pesqueira, Frédéric; Lévêque, Jean-Jacques; Thoré, Jean-Yves; Bes de Berc, Maxime; Sayadi, Jihane

    2016-04-01

    The GEOSCOPE observatory has provided continuous broadband data to the scientific community for the past 34 years. The 31 operational GEOSCOPE stations are installed in 17 countries, across all continents and on islands throughout the oceans. They are equipped with three component very broadband seismometers (STS1, T240 or STS2) and 24 or 26 bit digitizers (Q330HR). Seismometers are installed with warpless base plates, which decrease long period noise on horizontal components by up to 15dB. All stations send data in real time to the IPGP data center, which transmits them automatically to other data centers (FDSN/IRIS-DMC and RESIF) and tsunami warning centers. In 2016, three stations are expected to be installed or re-installed: in Western China (WUS station), in Saint Pierre and Miquelon Island (off the East coast of Canada) and in Walis and Futuna (SouthWest Pacific Ocean). The waveform data are technically validated by IPGP (25 stations) or EOST (6 stations) in order to check their continuity and integrity. Scientific data validation is also performed by analyzing seismic noise level of the continuous data and by comparing real and synthetic earthquake waveforms (body waves). After these validations, data are archived by the IPGP data center in Paris. They are made available to the international scientific community through different interfaces (see details on http://geoscope.ipgp.fr). Data are duplicated at the FDSN/IRIS-DMC data center and a similar duplication at the French national data center RESIF will be operational in 2016. The GEOSCOPE broadband seismic observatory also provides near-real time information on global moderate-to-large seismicity (above magnitude 5.5-6) through the automated application of the SCARDEC method (Vallée et al., 2011). By using global data from the FDSN - in particular from GEOSCOPE and IRIS/USGS stations -, earthquake source parameters (depth, moment magnitude, focal mechanism, source time function) are determined about 45

  16. EMSO: European Multidisciplinary Seafloor Observatory

    Science.gov (United States)

    Favali, Paolo

    2010-05-01

    EMSO, a Research Infrastructure listed within ESFRI (European Strategy Forum on Research Infrastructures) Roadmap (Report 2006, http://cordis.europa.eu/esfri/roadmap.htm), is the European-scale network of multidisciplinary seafloor observatories from the Arctic to the Black Sea with the scientific objective of long-term real-time monitoring of processes related to geosphere/biosphere/hydrosphere interactions. EMSO will enhance our understanding of processes through long time series appropriate to the scale of the phenomena, constituting the new frontier of studying Earth interior, deep-sea biology and chemistry and ocean processes. The development of an underwater network is based on previous EU-funded projects since early '90 and is being supported by several EU initiatives, as the on-going ESONET-NoE, coordinated by IFREMER (2007-2011, http://www.esonet-emso.org/esonet-noe/), and aims at gathering together the Research Community of the Ocean Observatories. In 2006 the FP7 Capacities Programme launched a call for Preparatory Phase (PP) projects, that will provide the support to create the legal and organisational entities in charge of managing the infrastructures, and coordinating the financial effort among the countries. Under this call the EMSO-PP project was approved in 2007 with the coordination of INGV and the participation of other 11 Institutions of 11 countries. The project has started in April 2008 and will last 4 years. The EMSO is a key-infrastructure both for Ocean Sciences and for Solid Earth Sciences. In this respect it will enhance and complement profitably the capabilities of other European research infrastructures such as EPOS, ERICON-Aurora Borealis, and SIOS. The perspective of the synergy among EMSO and other ESFRI Research Infrastructures will be outlined. EMSO Partners: IFREMER-Institut Français de Recherche pour l'exploitation de la mer (France, ref. Roland Person); KDM-Konsortium Deutsche Meeresforschung e.V. (Germany, ref. Christoph

  17. The Cenozoic Volcanoes in Northeast China

    Institute of Scientific and Technical Information of China (English)

    LIU Jiaqi; HAN Jingtai; GUO Zhengfu

    2002-01-01

    There are more than 600 Cenozoic volcanic cones and craters with abeut 50 000 km2of lava flows in northeast China, which formed many volcanic clusters and shown the features of the continental rift - type volcanoes. Most volcanic activities in this area, especially in the east part of Songliao graben, were usually controlled by rifts and faults with the main direction of NE / NNE in parallel and become younger from the central graben towards its both sides, especially to the east continental margin. It is revealed that the volcanism occurred in northeast China was as strong as that occurred in Japan during the Miocene and the Quaternary. The Quaternary basalt that is usually distributed along river valley is called "valley basalt"while Neogene basalt usually distributed in the top of mounts is called "high position basalt". These volcanoes and volcanic rocks are usually composed of alkaline basalts with ultramafic inclusions, except Changbaishan volcano that is built by trachyte and pantellerite.

  18. Living with Volcanoes: Year Eleven Teaching Resource Unit.

    Science.gov (United States)

    Le Heron, Kiri; Andrews, Jill; Hooks, Stacey; Larnder, Michele; Le Heron, Richard

    2000-01-01

    Presents a unit on volcanoes and experiences with volcanoes that helps students develop geography skills. Focuses on four volcanoes: (1) Rangitoto Island; (2) Lake Pupuke; (3) Mount Smart; and (4) One Tree Hill. Includes an answer sheet and resources to use with the unit. (CMK)

  19. How Do Volcanoes Affect Human Life? Integrated Unit.

    Science.gov (United States)

    Dayton, Rebecca; Edwards, Carrie; Sisler, Michelle

    This packet contains a unit on teaching about volcanoes. The following question is addressed: How do volcanoes affect human life? The unit covers approximately three weeks of instruction and strives to present volcanoes in an holistic form. The five subject areas of art, language arts, mathematics, science, and social studies are integrated into…

  20. Predicting the Timing and Location of the next Hawaiian Volcano

    Science.gov (United States)

    Russo, Joseph; Mattox, Stephen; Kildau, Nicole

    2010-01-01

    The wealth of geologic data on Hawaiian volcanoes makes them ideal for study by middle school students. In this paper the authors use existing data on the age and location of Hawaiian volcanoes to predict the location of the next Hawaiian volcano and when it will begin to grow on the floor of the Pacific Ocean. An inquiry-based lesson is also…

  1. A Bibliometric Analysis of Observatory Publications 2008-2012

    Science.gov (United States)

    Crabtree, D. R.

    2015-04-01

    Refereed publications are the primary output of modern observatories. I examine the productivity and impact of a significant number of observatories, as well as some other interesting aspects of observatory papers.

  2. Solar Imagery - Photosphere - Sunspot Drawings - McMath-Hulbert Observatory

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The McMath-Hulbert Observatory is a decommissioned solar observatory in Lake Angelus, Michigan, USA. It was established in 1929 as a private observatory by father...

  3. Volcanoes muon imaging using Cherenkov telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Catalano, O. [INAF, Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo, via U. La Malfa 153, I-90146 Palermo (Italy); Del Santo, M., E-mail: melania@ifc.inaf.it [INAF, Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo, via U. La Malfa 153, I-90146 Palermo (Italy); Mineo, T.; Cusumano, G.; Maccarone, M.C. [INAF, Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo, via U. La Malfa 153, I-90146 Palermo (Italy); Pareschi, G. [INAF Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807, Merate (Italy)

    2016-01-21

    A detailed understanding of a volcano inner structure is one of the key-points for the volcanic hazards evaluation. To this aim, in the last decade, geophysical radiography techniques using cosmic muon particles have been proposed. By measuring the differential attenuation of the muon flux as a function of the amount of rock crossed along different directions, it is possible to determine the density distribution of the interior of a volcano. Up to now, a number of experiments have been based on the detection of the muon tracks crossing hodoscopes, made up of scintillators or nuclear emulsion planes. Using telescopes based on the atmospheric Cherenkov imaging technique, we propose a new approach to study the interior of volcanoes detecting of the Cherenkov light produced by relativistic cosmic-ray muons that survive after crossing the volcano. The Cherenkov light produced along the muon path is imaged as a typical annular pattern containing all the essential information to reconstruct particle direction and energy. Our new approach offers the advantage of a negligible background and an improved spatial resolution. To test the feasibility of our new method, we have carried out simulations with a toy-model based on the geometrical parameters of ASTRI SST-2M, i.e. the imaging atmospheric Cherenkov telescope currently under installation onto the Etna volcano. Comparing the results of our simulations with previous experiments based on particle detectors, we gain at least a factor of 10 in sensitivity. The result of this study shows that we resolve an empty cylinder with a radius of about 100 m located inside a volcano in less than 4 days, which implies a limit on the magma velocity of 5 m/h.

  4. Volcanoes muon imaging using Cherenkov telescopes

    Science.gov (United States)

    Catalano, O.; Del Santo, M.; Mineo, T.; Cusumano, G.; Maccarone, M. C.; Pareschi, G.

    2016-01-01

    A detailed understanding of a volcano inner structure is one of the key-points for the volcanic hazards evaluation. To this aim, in the last decade, geophysical radiography techniques using cosmic muon particles have been proposed. By measuring the differential attenuation of the muon flux as a function of the amount of rock crossed along different directions, it is possible to determine the density distribution of the interior of a volcano. Up to now, a number of experiments have been based on the detection of the muon tracks crossing hodoscopes, made up of scintillators or nuclear emulsion planes. Using telescopes based on the atmospheric Cherenkov imaging technique, we propose a new approach to study the interior of volcanoes detecting of the Cherenkov light produced by relativistic cosmic-ray muons that survive after crossing the volcano. The Cherenkov light produced along the muon path is imaged as a typical annular pattern containing all the essential information to reconstruct particle direction and energy. Our new approach offers the advantage of a negligible background and an improved spatial resolution. To test the feasibility of our new method, we have carried out simulations with a toy-model based on the geometrical parameters of ASTRI SST-2M, i.e. the imaging atmospheric Cherenkov telescope currently under installation onto the Etna volcano. Comparing the results of our simulations with previous experiments based on particle detectors, we gain at least a factor of 10 in sensitivity. The result of this study shows that we resolve an empty cylinder with a radius of about 100 m located inside a volcano in less than 4 days, which implies a limit on the magma velocity of 5 m/h.

  5. Automatic identification of rockfalls and volcano-tectonic earthquakes at the Piton de la Fournaise volcano using a Random Forest algorithm

    Science.gov (United States)

    Hibert, Clément; Provost, Floriane; Malet, Jean-Philippe; Maggi, Alessia; Stumpf, André; Ferrazzini, Valérie

    2017-06-01

    Monitoring the endogenous seismicity of volcanoes helps to forecast eruptions and prevent their related risks, and also provides critical information on the eruptive processes. Due the high number of events recorded during pre-eruptive periods by the seismic monitoring networks, cataloging each event can be complex and time-consuming if done by human operators. Automatic seismic signal processing methods are thus essential to build consistent catalogs based on objective criteria. We evaluated the performance of the ;Random Forests; (RF) machine-learning algorithm for classifying seismic signals recorded at the Piton de la Fournaise volcano, La Réunion Island (France). We focused on the discrimination of the dominant event types (rockfalls and volcano-tectonic earthquakes) using over 19,000 events covering two time periods: 2009-2011 and 2014-2015. We parametrized the seismic signals using 60 attributes that were then given to RF algorithm. When the RF classifier was given enough training samples, its sensitivity (rate of good identification) exceeded 99%, and its performance remained high (above 90%) even with few training samples. The sensitivity collapsed when using an RF classifier trained with data from 2009 to 2011 to classify data from 2014 to 2015 catalog, because the physical characteristics of the rockfalls and hence their seismic signals had evolved between the two time-periods. The main attribute families (waveform, spectrum, spectrogram or polarization) were all found to be useful for event discrimination. Our work validates the performance of the RF algorithm and suggests it could be implemented at other volcanic observatories to perform automatic, near real-time, classification of seismic events.

  6. High-power actively Q-switched single-mode 1342 nm Nd:YVO4 ring laser, injection-locked by a cw single-frequency microchip laser.

    Science.gov (United States)

    Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

    2015-11-30

    In this paper we report on the realization of a single-mode Q-switched Nd:YVO4 ring laser at 1342 nm. Unidirectional and single-mode operation of the ring laser is achieved by injection-locking with a continuous wave Nd:YVO4 microchip laser, emitting a single-frequency power of up to 40 mW. The ring laser provides a single-mode power of 13.9 W at 10 kHz pulse repetition frequency with a pulse duration of 18.2 ns and an excellent beam quality (M2 laser, a power of 8.7 W at 671 nm with a pulse duration of 14.8 ns and a beam propagation factor of M2 < 1.1 is obtained. The 671 nm radiation features a long-term spectral width of 75 MHz.

  7. Up to 30 mW of broadly tunable CW green-to-orange light, based on sum-frequency mixing of Cr4+:forsterite and Nd:YVO4 lasers

    DEFF Research Database (Denmark)

    Mortensen, Jesper Liltorp; McWilliam, Alan; Leburn, Christopher G

    2006-01-01

    Efficient generation of continuous-wave (CW) tunable light in the yellow region is reported. The method is based on sum-frequency mixing of a tunable Cr4+:forsterite laser with a Nd:YVO4 laser. A periodically poled lithium niobate crystal was placed intra-cavity in a Nd:YVO4 laser, and the Cr4......+:forsterite laser was single-passed through the non-linear media. With this setup, it was possible to generate up to 3 mW of yellow light smoothly tunable from 573 to 587 nm. This is the highest output demonstrated to date for a tunable diode pumped solid-state CW laser in this wavelength region. The ways...

  8. Measurement of product of solid state laser materials by an alternative method: Application to Nd3+ doped YVO4 crystal for $^{4}F_{3/2}→ {}^{4}I_{11/2}$ transition

    Indian Academy of Sciences (India)

    P K Mukhopadhyay; Jogy George; S K Sharma; Rakesh Kapoor; T P S Nathan

    2001-01-01

    In this paper an alternative approach for measurement of product for $^{4}F_{3/2}→ {}^{4}I_{11/2}$ transition of Nd3+ doped YVO4 crystal is reported. In this method a microchip laser is formed by keeping a small piece of the sample in plane–plane resonator and a diode laser (808 nm) is used for pumping. The pump power induced thermal lensing effect is used to make the cavity stable. The cavity mode area is estimated by measuring the thermal lens focal length at the threshold and the average pump area is measured by Gaussian fit to the intensity profiles of the pump beam. The value of product of Nd:YVO4 crystal obtained by this method is within 10% of the reported values. The advantage of this method is that it is a simple method for direct measurement of product of laser crystals.

  9. The Malaysian Robotic Solar Observatory (P29)

    Science.gov (United States)

    Othman, M.; Asillam, M. F.; Ismail, M. K. H.

    2006-11-01

    Robotic observatory with small telescopes can make significant contributions to astronomy observation. They provide an encouraging environment for astronomers to focus on data analysis and research while at the same time reducing time and cost for observation. The observatory will house the primary 50cm robotic telescope in the main dome which will be used for photometry, spectroscopy and astrometry observation activities. The secondary telescope is a robotic multi-apochromatic refractor (maximum diameter: 15 cm) which will be housed in the smaller dome. This telescope set will be used for solar observation mainly in three different wavelengths simultaneously: the Continuum, H-Alpha and Calcium K-line. The observatory is also equipped with an automated weather station, cloud & rain sensor and all-sky camera to monitor the climatic condition, sense the clouds (before raining) as well as to view real time sky view above the observatory. In conjunction with the Langkawi All-Sky Camera, the observatory website will also display images from the Malaysia - Antarctica All-Sky Camera used to monitor the sky at Scott Base Antarctica. Both all-sky images can be displayed simultaneously to show the difference between the equatorial and Antarctica skies. This paper will describe the Malaysian Robotic Observatory including the systems available and method of access by other astronomers. We will also suggest possible collaboration with other observatories in this region.

  10. The Role of Crustal Tectonics in Volcano Dynamics (ROCTEVODY) along the Southern Andes: seismological study with emphasis on Villarrica Volcano

    Science.gov (United States)

    Mora-Stock, Cindy; Tassara, Andrés

    2016-04-01

    -Villarrica Fault (MVF). The extensional characteristics of previous eruptions at Villarrica contrasts with the dextral strike-slip motion of LOFZ and the compressive regime dominated by the subduction. Then, this projects aims to understand how the NW-SE inherited structures interacts with their intra-arc counterpart to allow the emplacement of volcanic edifices under the present day compressive stress regime. This goal will be achieved through the analysis of a seismic database for Villarrica volcano that combines data from a dense local network and the network of the Chilean volcanic observatory. These data will allow us to identify long period events and tremor signals from which we plan to perform a wave field characterization to extract information about fluid flow and seismic source, together with a precise location of tectonic crustal events. We will present preliminary results and a conceptual model to explain the role of the different structures at interplay in the region and their relation with volcano dynamics.

  11. Lyman Alpha Spicule Observatory (LASO)

    Science.gov (United States)

    Chamberlin, P. C.; Allred, J. C.; Airapetian, V.; Gong, Q.; Mcintosh, S. W.; De Pontieu, B.; Fontenla, J. M.

    2011-12-01

    The Lyman Alpha Spicule Observatory (LASO) sounding rocket will observe small-scale eruptive events called "Rapid Blue-shifted Events" (RBEs) [Rouppe van der Voort et al., 2009], the on-disk equivalent of Type-II spicules, and extend observations that explore their role in the solar coronal heating problem [De Pontieu et al., 2011]. LASO utilizes a new and novel optical design to simultaneously observe two spatial dimensions at 4.2" spatial resolution (2.1" pixels) over a 2'x2' field of view with high spectral resolution of 66mÅ (33mÅ pixels) across a broad 20Å spectral window. This spectral window contains three strong chromospheric and transition region emissions and is centered on the strong Hydrogen Lyman-α emission at 1216Å. This instrument makes it possible to obtain new data crucial to the physical understanding of these phenomena and their role in the overall energy and momentum balance from the upper chromosphere to lower corona. LASO was submitted March 2011 in response to the ROSES SHP-LCAS call.

  12. The Jiangmen Underground Neutrino Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Sawatzki, Julia [Technische Universitaet Muenchen, Physik Department E15, James-Franck-Strasse 1, 85748 Garching (Germany)

    2016-07-01

    The Jiangmen Underground Neutrino Observatory (JUNO) is a next-generation medium-baseline reactor neutrino experiment located in southern China, close to Kaiping. The construction of the 700 m deep underground facility already started and the experiment is scheduled to start data-taking in 2020, and is expected to operate for at least 20 years. The 20 kt liquid scintillator detector will detect low-energy neutrinos with an unprecedented energy resolution of 3% (at 1 MeV). The primary experimental goal is the determination of the neutrino mass hierarchy at 3σ significance from the measurement of the reactor neutrino energy spectrum. Two nuclear power plants: Yangjiang and Taishan are located at a distance of ∝ 53 km from the detector. Moreover, JUNO will measure the solar neutrino mixing parameters and the atmospheric neutrino squared-mass splitting with a precision < 1%. In addition, supernova neutrinos, geo-neutrinos, sterile neutrinos as well as solar and atmospheric neutrinos can be studied. This talk reviews the status of the project and highlight important scientific objectives.

  13. Strainmeters at Moxa observatory, Germany

    Science.gov (United States)

    Jahr, Thomas; Kroner, Corinna; Lippmann, Andrea

    2006-01-01

    Since 1997, two quartz tube strainmeters at the Geodynamic Observatory Moxa, located 30 km south of Jena, are used to observe long-period horizontal deformation signals. Both strainmeters are 26 m long with orientations NS and EW and are installed in a gallery. To this system a third component was added in 1999, which connects the ends of the quartz tubes diagonally. This component is realised as a laser strainmeter, running through a 38 m long horizontal borehole. The first data analyses show high signal-to-noise ratios for the tidal frequencies and also the free oscillations caused by the Sumatra earthquake in December 2004 are clearly detectable. It can be shown that the quartz strainmeter extending in EW direction generally contains significant more noise induced by barometric pressure than the NS-component. The laser strainmeter record shows strong influences of changing barometric pressure, due to the fact that the beam does not run in a vacuum. This influence is reduced in the higher frequencies by sealing the ends of the horizontal borehole with high quality glass. In addition, the observations are clearly temperature dependent and the influence of rainfall could be verified by two irrigation experiments.

  14. Selected time-lapse movies of the east rift zone eruption of KĪlauea Volcano, 2004–2008

    Science.gov (United States)

    Orr, Tim R.

    2011-01-01

    Since 2004, the U.S. Geological Survey's Hawaiian Volcano Observatory has used mass-market digital time-lapse cameras and network-enabled Webcams for visual monitoring and research. The 26 time-lapse movies in this report were selected from the vast collection of images acquired by these camera systems during 2004–2008. Chosen for their content and broad aesthetic appeal, these image sequences document a variety of flow-field and vent processes from Kīlauea's east rift zone eruption, which began in 1983 and is still (as of 2011) ongoing.

  15. Volcano geodesy in the Cascade arc, USA

    Science.gov (United States)

    Poland, Michael P.; Lisowski, Michael; Dzurisin, Daniel; Kramer, Rebecca; McLay, Megan; Pauk, Ben

    2017-08-01

    Experience during historical time throughout the Cascade arc and the lack of deep-seated deformation prior to the two most recent eruptions of Mount St. Helens might lead one to infer that Cascade volcanoes are generally quiescent and, specifically, show no signs of geodetic change until they are about to erupt. Several decades of geodetic data, however, tell a different story. Ground- and space-based deformation studies have identified surface displacements at five of the 13 major Cascade arc volcanoes that lie in the USA (Mount Baker, Mount St. Helens, South Sister, Medicine Lake, and Lassen volcanic center). No deformation has been detected at five volcanoes (Mount Rainier, Mount Hood, Newberry Volcano, Crater Lake, and Mount Shasta), and there are not sufficient data at the remaining three (Glacier Peak, Mount Adams, and Mount Jefferson) for a rigorous assessment. In addition, gravity change has been measured at two of the three locations where surveys have been repeated (Mount St. Helens and Mount Baker show changes, while South Sister does not). Broad deformation patterns associated with heavily forested and ice-clad Cascade volcanoes are generally characterized by low displacement rates, in the range of millimeters to a few centimeters per year, and are overprinted by larger tectonic motions of several centimeters per year. Continuous GPS is therefore the best means of tracking temporal changes in deformation of Cascade volcanoes and also for characterizing tectonic signals so that they may be distinguished from volcanic sources. Better spatial resolution of volcano deformation can be obtained through the use of campaign GPS, semipermanent GPS, and interferometric synthetic aperture radar observations, which leverage the accumulation of displacements over time to improve signal to noise. Deformation source mechanisms in the Cascades are diverse and include magma accumulation and withdrawal, post-emplacement cooling of recent volcanic deposits, magmatic

  16. Volcano geodesy in the Cascade arc, USA

    Science.gov (United States)

    Poland, Michael; Lisowski, Michael; Dzurisin, Daniel; Kramer, Rebecca; McLay, Megan; Pauk, Benjamin

    2017-01-01

    Experience during historical time throughout the Cascade arc and the lack of deep-seated deformation prior to the two most recent eruptions of Mount St. Helens might lead one to infer that Cascade volcanoes are generally quiescent and, specifically, show no signs of geodetic change until they are about to erupt. Several decades of geodetic data, however, tell a different story. Ground- and space-based deformation studies have identified surface displacements at five of the 13 major Cascade arc volcanoes that lie in the USA (Mount Baker, Mount St. Helens, South Sister, Medicine Lake, and Lassen volcanic center). No deformation has been detected at five volcanoes (Mount Rainier, Mount Hood, Newberry Volcano, Crater Lake, and Mount Shasta), and there are not sufficient data at the remaining three (Glacier Peak, Mount Adams, and Mount Jefferson) for a rigorous assessment. In addition, gravity change has been measured at two of the three locations where surveys have been repeated (Mount St. Helens and Mount Baker show changes, while South Sister does not). Broad deformation patterns associated with heavily forested and ice-clad Cascade volcanoes are generally characterized by low displacement rates, in the range of millimeters to a few centimeters per year, and are overprinted by larger tectonic motions of several centimeters per year. Continuous GPS is therefore the best means of tracking temporal changes in deformation of Cascade volcanoes and also for characterizing tectonic signals so that they may be distinguished from volcanic sources. Better spatial resolution of volcano deformation can be obtained through the use of campaign GPS, semipermanent GPS, and interferometric synthetic aperture radar observations, which leverage the accumulation of displacements over time to improve signal to noise. Deformation source mechanisms in the Cascades are diverse and include magma accumulation and withdrawal, post-emplacement cooling of recent volcanic deposits, magmatic

  17. From high quality seismic data acquisition in remote volcanic area to fast data distribution to scientific community: The UnderVolc project on Piton de la Fournaise volcano

    Science.gov (United States)

    Brenguier, Florent; Kowalski, Philippe; Pequegnat, Catherine; Lauret, Frédéric; Cougoulat, Glenn; Boissier, Patrice; Catherine, Philippe

    2010-05-01

    Piton de la Fournaise basaltic volcano (La Réunion island, France) is one of the most active volcano in the world with an average of one eruption every year. This volcano is thus an ideal case study for research projects focusing on studying magmatic, seismic and deformation processes occurring in volcanic areas. The UNDERVOLC (UNDERstanding VOLCanic Processes) research project main goal is to provide high quality 3-component broadband continuous seismic data to an amount of about 30 volcano-seismologists from different international research teams (including Japan and New-Zealand). This data acquisition system is moreover dedicated to the monitoring of Piton de la Fournaise volcano by providing real-time seismic data to the Piton de la Fournaise volcanological Observatory/IPGP. The network consists of 21 fully autonomous stations composed of CMG40-T seismometers associated to high dynamic digitizers and linked to wireless digital radio stations. The seismic signal is sent by UDP protocol to the observatory through a network of wireless LAN over large distances (~10 km) and possibly through the internet to the Observatory. The acquisition system at the observatory is composed of: 1-An Earthworm system (USGS - ISTI - CERI) with a Q330 to Earthworm data acquisition module (6 permanent stations from the observatory) 2-An Apollo server system (Nanometrics) for 15 stations (for which seismometers and digitizers belong to the French national pool of portable seismic instruments Sismob, INSU-CNRS) In both case, requests are sent back to the stations in case of loss of udp packets. This system allows us producing miniseed files every hour. Since September 2009, the full dataset has less then 1 % of gaps. In order to provide a fast data access to the scientific community, we synchronize our dataset every night with the SISMOB datacenter located in France (LGIT, Grenoble). After a quality check, seed data volumes are produced and distributed by standard NETDC requests from

  18. Byurakan Astrophysical Observatory as Cultural Centre

    Science.gov (United States)

    Mickaelian, A. M.; Farmanyan, S. V.

    2016-12-01

    NAS RA V. Ambartsumian Byurakan Astrophysical Observatory is presented as a cultural centre for Armenia and the Armenian nation in general. Besides being scientific and educational centre, the Observatory is famous for its unique architectural ensemble, rich botanical garden and world of birds, as well as it is one of the most frequently visited sightseeing of Armenia. In recent years, the Observatory has also taken the initiative of the coordination of the Cultural Astronomy in Armenia and in this field, unites the astronomers, historians, archaeologists, ethnographers, culturologists, literary critics, linguists, art historians and other experts.

  19. Volcano shapes, entropies, and eruption probabilities

    Science.gov (United States)

    Gudmundsson, Agust; Mohajeri, Nahid

    2014-05-01

    We propose that the shapes of polygenetic volcanic edifices reflect the shapes of the associated probability distributions of eruptions. In this view, the peak of a given volcanic edifice coincides roughly with the peak of the probability (or frequency) distribution of its eruptions. The broadness and slopes of the edifices vary widely, however. The shapes of volcanic edifices can be approximated by various distributions, either discrete (binning or histogram approximation) or continuous. For a volcano shape (profile) approximated by a normal curve, for example, the broadness would be reflected in its standard deviation (spread). Entropy (S) of a discrete probability distribution is a measure of the absolute uncertainty as to the next outcome/message: in this case, the uncertainty as to time and place of the next eruption. A uniform discrete distribution (all bins of equal height), representing a flat volcanic field or zone, has the largest entropy or uncertainty. For continuous distributions, we use differential entropy, which is a measure of relative uncertainty, or uncertainty change, rather than absolute uncertainty. Volcano shapes can be approximated by various distributions, from which the entropies and thus the uncertainties as regards future eruptions can be calculated. We use the Gibbs-Shannon formula for the discrete entropies and the analogues general formula for the differential entropies and compare their usefulness for assessing the probabilities of eruptions in volcanoes. We relate the entropies to the work done by the volcano during an eruption using the Helmholtz free energy. Many factors other than the frequency of eruptions determine the shape of a volcano. These include erosion, landslides, and the properties of the erupted materials (including their angle of repose). The exact functional relation between the volcano shape and the eruption probability distribution must be explored for individual volcanoes but, once established, can be used to

  20. Temperature effect on transmissivity of two Grand-YVO4 prism%两种格兰型钒酸钇棱镜透射比的温度效应

    Institute of Scientific and Technical Information of China (English)

    方明; 张共年; 李华

    2011-01-01

    To investigate the temperature effect upon transmissivity of the two YVO4 prisms, this study applies theoretical calculation and analysis, as well as experimental verification and comparison method. The result shows that the theoretical value is consistent with the experimental value and the temperature of YVO4 prism is stable. Temperature has less impact on Glan-Foucault prism than Glan-Tomson prism. This provides an important reference value to the application of YVO4 prism in engineering experiment.%为了研究温度对两种钒酸钇棱镜透射比的影响,采用理论计算与分析的方法,并通过实验验证,进行数据对比。结果表明:理论值与实验值符合,钒酸钇棱镜的温度稳定性好,温度对格兰·付科型钒酸钇棱镜的透射比比格兰·汤姆逊型钒酸钇棱镜透射比影响更小,这为钒酸钇棱镜在工程实验中的应用提供了重要的参考价值。

  1. Principal component analysis vs. self-organizing maps combined with hierarchical clustering for pattern recognition in volcano seismic spectra

    Science.gov (United States)

    Unglert, K.; Radić, V.; Jellinek, A. M.

    2016-06-01

    Variations in the spectral content of volcano seismicity related to changes in volcanic activity are commonly identified manually in spectrograms. However, long time series of monitoring data at volcano observatories require tools to facilitate automated and rapid processing. Techniques such as self-organizing maps (SOM) and principal component analysis (PCA) can help to quickly and automatically identify important patterns related to impending eruptions. For the first time, we evaluate the performance of SOM and PCA on synthetic volcano seismic spectra constructed from observations during two well-studied eruptions at Klauea Volcano, Hawai'i, that include features observed in many volcanic settings. In particular, our objective is to test which of the techniques can best retrieve a set of three spectral patterns that we used to compose a synthetic spectrogram. We find that, without a priori knowledge of the given set of patterns, neither SOM nor PCA can directly recover the spectra. We thus test hierarchical clustering, a commonly used method, to investigate whether clustering in the space of the principal components and on the SOM, respectively, can retrieve the known patterns. Our clustering method applied to the SOM fails to detect the correct number and shape of the known input spectra. In contrast, clustering of the data reconstructed by the first three PCA modes reproduces these patterns and their occurrence in time more consistently. This result suggests that PCA in combination with hierarchical clustering is a powerful practical tool for automated identification of characteristic patterns in volcano seismic spectra. Our results indicate that, in contrast to PCA, common clustering algorithms may not be ideal to group patterns on the SOM and that it is crucial to evaluate the performance of these tools on a control dataset prior to their application to real data.

  2. Integration Of Low-Cost Single-Frequency GPS Stations Using 'Spider' Technology Within Existing Dual-Frequency GPS Network at Soufrière Hills Volcano, Montserrat (West Indies): Processing And Results

    Science.gov (United States)

    Pascal, K.; Palamartchouk, K.; Lahusen, R. G.; Young, K.; Voight, B.

    2015-12-01

    Twenty years ago, began the eruption of the explosive Soufrière Hills Volcano, dominating the southern part of the island of Montserrat, West Indies. Five phases of effusive activity have now occurred, characterized by dome building and collapse, causing numerous evacuations and the emigration of half of the population. Over the years, the volcano monitoring network has greatly expanded. The GPS network, started from few geodetic markers, now consists of 14 continuous dual frequency GPS stations, distributed on and around the edifice, where topography and vegetation allow. The continuous GPS time series have given invaluable insight into the volcano behavior, notably revealing deflation/inflation cycles corresponding to phases and pauses of effusive activity, respectively. In 2014, collaboration of the CALIPSO Project (Penn State; NSF) with the Montserrat Volcano Observatory enriched the GPS and seismic monitoring networks with six 'spider' stations. The 'spiders', developed by R. Lahusen at Cascades Volcano Observatory, are designed to be deployed easily in rough areas and combine a low cost seismic station and a L1-only GPS station. To date, three 'spiders' have been deployed on Soufrière Hills Volcano, the closest at ~1 km from the volcanic conduit, adjacent to a lava lobe on the dome. Here we present the details of GPS data processing in a network consisting of both dual and single frequency receivers ('spiders') using GAMIT/GLOBK software. Processing together single and dual frequency data allowed their representation in a common reference frame, and a meaningful geophysical interpretation of all the available data. We also present the 'spiders' time series along with the results from the rest of the network and examine if any significant deformation, correlating with other manifestations of volcanic activity, has been recorded by the 'spiders' since deployment. Our results demonstrate that low cost GNSS equipment can serve as valuable components in volcano

  3. Growth and degradation of Hawaiian volcanoes: Chapter 3 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Clague, David A.; Sherrod, David R.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    The 19 known shield volcanoes of the main Hawaiian Islands—15 now emergent, 3 submerged, and 1 newly born and still submarine—lie at the southeast end of a long-lived hot spot chain. As the Pacific Plate of the Earth’s lithosphere moves slowly northwestward over the Hawaiian hot spot, volcanoes are successively born above it, evolve as they drift away from it, and eventually die and subside beneath the ocean surface.

  4. The Arecibo Observatory Space Academy

    Science.gov (United States)

    Rodriguez-Ford, Linda A.; Fernanda Zambrano Marin, Luisa; Aponte Hernandez, Betzaida; Soto, Sujeily; Rivera-Valentin, Edgard G.

    2016-10-01

    The Arecibo Observatory Space Academy (AOSA) is an intense fifteen-week pre-college research program for qualified high school students residing in Puerto Rico, which includes ten days for hands-on, on site research activities. Our mission is to prepare students for their professional careers by allowing them to receive an independent and collaborative research experience on topics related to the multidisciplinary field of space science. Our objectives are to (1) supplement the student's STEM education via inquiry-based learning and indirect teaching methods, (2) immerse students in an ESL environment, further developing their verbal and written presentation skills, and (3) foster in every student an interest in the STEM fields by harnessing their natural curiosity and knowledge in order to further develop their critical thinking and investigation skills. Students interested in participating in the program go through an application, interview and trial period before being offered admission. They are welcomed as candidates the first weeks, and later become cadets while experiencing designing, proposing, and conducting research projects focusing in fields like Physics, Astronomy, Geology, Chemistry, and Engineering. Each individual is evaluated with program compatibility based on peer interaction, preparation, participation, and contribution to class, group dynamics, attitude, challenges, and inquiry. This helps to ensure that specialized attention can be given to students who demonstrate a dedication and desire to learn. Deciding how to proceed in the face of setbacks and unexpected problems is central to the learning experience. At the end of the semester, students present their research to the program mentors, peers, and scientific staff. This year, AOSA students also focused on science communication and were trained by NASA's FameLab. Students additionally presented their research at this year's International Space Development Conference (ISDC), which was held in

  5. Were megalithic tombs solar observatories?

    Science.gov (United States)

    Hänel, Andreas

    The orientations of the entrances of several hundred neolithic tombs in Northwest Germany, the Netherlands, Bretagne (Brittany) and the eastern Pyrenees (Roussillon and Catalunya) have been measured with a compass. Comparing these measurements with other authors, we could determine systematic errors and combine the measurements. The results are presented as polar coordinate histograms. The passage graves of Northwest Germany and the Netherlands are oriented east-west. For some of the tombs, entrances are preserved always on the southern side. We assume therefore, that all tombs had entrances on the southern side and we conclude that they are mainly oriented to the south, the direction where celestial objects, and especially the sun, reach their highest position in the sky. Similar results were found by Hamel (1985) for tombs in Mecklenburg-Vorpommern. The tombs in Brittany show a different orientation to the southeast, the azimuth of the rising sun on winter solstice. Tombs in the eastern Pyrenees have a similar orientation, as has also been found by other authors for several regions in southern France and the Iberian peninsula (Iund 2002, Chevalier 1999, Hoskin 2002). But in the eastern Pyrenees and from there north to the Provence and on the Balearic Islands exists a group of tombs that are oriented towards the southwest, where the winter sun sets (Chevalier 1999). But most of the entrances of the tombs are oriented towards the sun. The tombs certainly were no precise astronomical observatories, but their orientations might have had a ritual reason and the course of the sun in the sky was well known at that time.

  6. The Solar Dynamics Observatory (SDO)

    Science.gov (United States)

    Pesnell, W. Dean; Thompson, B. J.; Chamberlin, P. C.

    2012-01-01

    The Solar Dynamics Observatory (SDO) was launched on 11 February 2010 at 15:23 UT from Kennedy Space Center aboard an Atlas V 401 (AV-021) launch vehicle. A series of apogee-motor firings lifted SDO from an initial geosynchronous transfer orbit into a circular geosynchronous orbit inclined by 28° about the longitude of the SDO-dedicated ground station in New Mexico. SDO began returning science data on 1 May 2010. SDO is the first space-weather mission in NASA’s Living With a Star (LWS) Program. SDO’s main goal is to understand, driving toward a predictive capability, those solar variations that influence life on Earth and humanity’s technological systems. The SDO science investigations will determine how the Sun’s magnetic field is generated and structured, how this stored magnetic energy is released into the heliosphere and geospace as the solar wind, energetic particles, and variations in the solar irradiance. Insights gained from SDO investigations will also lead to an increased understanding of the role that solar variability plays in changes in Earth’s atmospheric chemistry and climate. The SDO mission includes three scientific investigations (the Atmospheric Imaging Assembly (AIA), Extreme Ultraviolet Variability Experiment (EVE), and Helioseismic and Magnetic Imager (HMI)), a spacecraft bus, and a dedicated ground station to handle the telemetry. The Goddard Space Flight Center built and will operate the spacecraft during its planned five-year mission life; this includes: commanding the spacecraft, receiving the science data, and forwarding that data to the science teams. The science investigations teams at Stanford University, Lockheed Martin Solar Astrophysics Laboratory (LMSAL), and University of Colorado Laboratory for Atmospheric and Space Physics (LASP) will process, analyze, distribute, and archive the science data. We will describe the building of SDO and the science that it will provide to NASA.

  7. Insights on volcanic behaviour from the 2015 July 23-24 T-phase signals generated by eruptions at Kick-'em-Jenny Submarine Volcano, Grenada, Lesser Antilles

    Science.gov (United States)

    Dondin, F. J. Y.; Latchman, J. L.; Robertson, R. E. A.; Lynch, L.; Stewart, R.; Smith, P.; Ramsingh, C.; Nath, N.; Ramsingh, H.; Ash, C.

    2015-12-01

    Kick-'em-Jenny volcano (KeJ) is the only known active submarine volcano in the Lesser Antilles Arc. Since 1939, the year it revealed itself, and until the volcano-seismic unrest of 2015 July 11-25 , the volcano has erupted 12 times. Only two eruptions breached the surface: 1939, 1974. The volcano has an average eruption cycle of about 10-11 years. Excluding the Montserrat, Soufrière Hills, KeJ is the most active volcano in the Lesser Antilles arc. The University of the West Indies, Seismic Research Centre (SRC) has been monitoring KeJ since 1953. On July 23 and 24 at 1:42 am and 0:02 am local time, respectively, the SRC recorded T-phase signals , considered to have been generated by KeJ. Both signals were recorded at seismic stations in and north of Grenada: SRC seismic stations as well as the French volcano observatories in Guadeloupe and Martinique, Montserrat Volcano Observatory, and the Puerto Rico Seismic Network. These distant recordings, along with the experience of similar observations in previous eruptions, allowed the SRC to confirm that two explosive eruptions occurred in this episode at KeJ. Up to two days after the second eruption, when aerial surveillance was done, there was no evidence of activity at the surface. During the instrumental era, eruptions of the KeJ have been identified from T-phases recorded at seismic stations from Trinidad, in the south, to Puerto Rico, in the north. In the 2015 July eruption episode, the seismic station in Trinidad did not record T-phases associated with the KeJ eruptions. In this study we compare the T-phase signals of 2015 July with those recorded in KeJ eruptions up to 1974 to explore possible causative features for the T-phase recording pattern in KeJ eruptions. In particular, we investigate the potential role played by the Sound Fixing and Ranging (SOFAR) layer in influencing the absence of the T-phase on the Trinidad seismic station during this eruption.

  8. Astronomy projects in ruins as observatory obliterated

    CERN Multimedia

    Bradley, M

    2003-01-01

    Canberra bushfires have gutted the Mount Stromlo Observatory causing the flames destroyed five telescopes, the workshop, eight staff homes and the main dome, causing more than $20 million in damage (1 page).

  9. Cesarsky tipped to head Euro observatory

    CERN Multimedia

    1998-01-01

    French astrophysicist Catherine Cesarsky is the most likely candidate to be the next director of the European Southern Observatory in Garching. She is director of fundamental science at France's atomic energy research organization.

  10. Margaret Huggins and Tulse Hill Observatory

    Science.gov (United States)

    Becker, Barbara J.

    2016-04-01

    Photography, instrument design, methodology, interpretation - all skills brought to William Huggins' observatory by his persistent and careful wife Margaret. Together they developed spectroscopy into a powerful research tool. Barbara Becker tells the story.

  11. Muons reveal the interior of volcanoes

    CERN Multimedia

    Francesco Poppi

    2010-01-01

    The MU-RAY project has the very challenging aim of providing a “muon X-ray” of the Vesuvius volcano (Italy) using a detector that records the muons hitting it after traversing the rock structures of the volcano. This technique was used for the first time in 1971 by the Nobel Prize-winner Louis Alvarez, who was searching for unknown burial chambers in the Chephren pyramid.   The location of the muon detector on the slopes of the Vesuvius volcano. Like X-ray scans of the human body, muon radiography allows researchers to obtain an image of the internal structures of the upper levels of volcanoes. Although such an image cannot help to predict ‘when’ an eruption might occur, it can, if combined with other observations, help to foresee ‘how’ it could develop and serves as a powerful tool for the study of geological structures. Muons come from the interaction of cosmic rays with the Earth's atmosphere. They are able to traverse layers of ro...

  12. The reawakening of Alaska's Augustine volcano

    Science.gov (United States)

    Power, John A.; Nye, Christopher J.; Coombs, Michelle L.; Wessels, Rick L.; Cervelli, Peter F.; Dehn, Jon; Wallace, Kristi L.; Freymueller, Jeffrey T.; Doukas, Michael P.

    2006-01-01

    Augustine volcano, in south central Alaska, ended a 20-year period of repose on 11 January 2006 with 13 explosive eruptions in 20 days. Explosive activity shifted to a quieter effusion of lava in early February, forming a new summit lava dome and two short, blocky lava flows by late March (Figure 1).

  13. Volcano hazards at Fuego and Acatenango, Guatemala

    Science.gov (United States)

    Vallance, J.W.; Schilling, S.P.; Matías, O.; Rose, William I.; Howell, M.M.

    2001-01-01

    The Fuego-Acatenango massif comprises a string of five or more volcanic vents along a north-south trend that is perpendicular to that of the Central American arc in Guatemala. From north to south known centers of volcanism are Ancient Acatenango, Yepocapa, Pico Mayor de Acatenango, Meseta, and Fuego. Volcanism along the trend stretches back more than 200,000 years. Although many of the centers have been active contemporaneously, there is a general sequence of younger volcanism, from north to south along the trend. This massive volcano complex towers more than 3500 meters (m) above the Pacific coastal plain to the south and 2000 m above the Guatemalan Highlands to the north. The volcano complex comprises remnants of multiple eruptive centers, which periodically have collapsed to form huge debris avalanches. The largest of these avalanches extended more than 50 kilometers (km) from its source and covered more than 300 square km. The volcano has potential to produce huge debris avalanches that could inundate large areas of the Pacific coastal plain. In areas around the volcanoes and downslope toward the coastal plain, more than 100,000 people are potentially at risk from these and other flowage phenomena.

  14. New volcanoes discovered in southeast Australia

    Science.gov (United States)

    Wendel, JoAnna

    2014-07-01

    Scientists have discovered three new active volcanoes in the Newer Volcanics Province (NVP) in southeast Australia. Researchers from Monash University in Melbourne describe in the Australian Journal of Earth Sciences how they used a combination of satellite photographs, detailed topography models from NASA, the distribution of magnetic minerals in the rocks, and site visits to analyze the region.

  15. Carbonate assimilation at Merapi volcano, Java Indonesia

    DEFF Research Database (Denmark)

    Chadwick, J.P; Troll, V.R; Ginibre,, C.

    2007-01-01

    Recent basaltic andesite lavas from Merapi volcano contain abundant, complexly zoned, plagioclase phenocrysts, analysed here for their petrographic textures, major element composition and Sr isotope composition. Anorthite (An) content in individual crystals can vary by as much as 55 mol% (An40^95...

  16. Degassing and differentiation in subglacial volcanoes, Iceland

    Science.gov (United States)

    Moore, J.G.; Calk, L.C.

    1991-01-01

    Within the neovolcanic zones of Iceland many volcanoes grew upward through icecaps that have subsequently melted. These steep-walled and flat-topped basaltic subglacial volcanoes, called tuyas, are composed of a lower sequence of subaqueously erupted, pillowed lavas overlain by breccias and hyaloclastites produced by phreatomagmatic explosions in shallow water, capped by a subaerially erupted lava plateau. Glass and whole-rock analyses of samples collected from six tuyas indicate systematic variations in major elements showing that the individual volcanoes are monogenetic, and that commonly the tholeiitic magmas differentiated and became more evolved through the course of the eruption that built the tuya. At Herdubreid, the most extensively studies tuya, the upward change in composition indicates that more than 50 wt.% of the first erupted lavas need crystallize over a range of 60??C to produce the last erupted lavas. The S content of glass commonly decreases upward in the tuyas from an average of about 0.08 wt.% at the base to crystallization that generates the more evolved, lower-temperature melts during the growth of the tuyas, apparently results from cooling and degassing of magma contained in shallow magma chambers and feeders beneath the volcanoes. Cooling may result from percolation of meltwater down cracks, vaporization, and cycling in a hydrothermal circulation. Degassing occurs when progressively lower pressure eruption (as the volcanic vent grows above the ice/water surface) lowers the volatile vapour pressure of subsurface melt, thus elevating the temperature of the liquidus and hastening liquid-crystal differentiation. ?? 1991.

  17. Web-based volcano monitoring data from the Pu‘u ‘O‘o eruptive vent (Kilauea Volcano, Hawai‘i) as a tool for geoscience education

    Science.gov (United States)

    Poland, M. P.; Townson, R.; Loren, A.; Brooks, B. A.; Foster, J. H.

    2009-12-01

    A significant challenge in college and university geoscience courses is conveying the dynamic nature of the Earth to students. The Internet, however, offers an opportunity to engage classes by making accessible the best examples of current geologic activity, regardless of location. In volcanology, Kilauea, Hawai‘i, is well known as one of the most active volcanoes in the world, and the Web site for the U.S. Geological Survey’s Hawaiian Volcano Observatory offers a daily update of volcanic activity that is followed by people around the globe. The Pu‘u ‘O‘o eruptive vent, on Kilauea‘s east rift zone, has been the focus of near continuous eruption since 1983, experiencing cycles of growth and collapse, high lava fountains, lava lakes, and other phenomena over the course of its existence. To track volcanic activity, various types of monitoring instruments have been installed on and around Pu‘u ‘O‘o, including (as of August 2009) two webcams, one short-period seismometer, one broadband seismometer, seven continuous GPS stations, and two continuous borehole tiltmeters. Monitoring data from Pu‘u ‘O‘o will be made available via the Internet as part of a collaborative research and education project between the Hawaiian Volcano Observatory, National Aeronautics and Space Administration, and University of Hawai‘i at Mānoa. The educational Web site is intended for use in college and university courses, from introductory science classes to graduate-level seminars. Scheduled to come on line by fall 2009, the Web site will provide tools to explore current monitoring results from the eruptive vent. Geophysical data, such as GPS, seismic, and tilt measurements, will be accessible via a time-series query tool, and the complete archive of webcam imagery will be available for examination of visual changes in volcanic activity over time. The Web site will also include background information and references concerning the 1983-present eruption, descriptions of

  18. A Green Robotic Observatory for Astronomy Education

    Science.gov (United States)

    Reddy, Vishnu; Archer, K.

    2008-09-01

    With the development of robotic telescopes and stable remote observing software, it is currently possible for a small institution to have an affordable astronomical facility for astronomy education. However, a faculty member has to deal with the light pollution (observatory location on campus), its nightly operations and regular maintenance apart from his day time teaching and research responsibilities. While building an observatory at a remote location is a solution, the cost of constructing and operating such a facility, not to mention the environmental impact, are beyond the reach of most institutions. In an effort to resolve these issues we have developed a robotic remote observatory that can be operated via the internet from anywhere in the world, has a zero operating carbon footprint and minimum impact on the local environment. The prototype observatory is a clam-shell design that houses an 8-inch telescope with a SBIG ST-10 CCD detector. The brain of the observatory is a low draw 12-volt harsh duty computer that runs the dome, telescope, CCD camera, focuser, and weather monitoring. All equipment runs of a 12-volt AGM-style battery that has low lead content and hence more environmental-friendly to dispose. The total power of 12-14 amp/hrs is generated from a set of solar panels that are large enough to maintain a full battery charge for several cloudy days. This completely eliminates the need for a local power grid for operations. Internet access is accomplished via a high-speed cell phone broadband connection or satellite link eliminating the need for a phone network. An independent observatory monitoring system interfaces with the observatory computer during operation. The observatory converts to a trailer for transportation to the site and is converted to a semi-permanent building without wheels and towing equipment. This ensures minimal disturbance to local environment.

  19. Hazard maps of Colima volcano, Mexico

    Science.gov (United States)

    Suarez-Plascencia, C.; Nunez-Cornu, F. J.; Escudero Ayala, C. R.

    2011-12-01

    Colima volcano, also known as Volcan de Fuego (19° 30.696 N, 103° 37.026 W), is located on the border between the states of Jalisco and Colima and is the most active volcano in Mexico. Began its current eruptive process in February 1991, in February 10, 1999 the biggest explosion since 1913 occurred at the summit dome. The activity during the 2001-2005 period was the most intense, but did not exceed VEI 3. The activity resulted in the formation of domes and their destruction after explosive events. The explosions originated eruptive columns, reaching attitudes between 4,500 and 9,000 m.a.s.l., further pyroclastic flows reaching distances up to 3.5 km from the crater. During the explosive events ash emissions were generated in all directions reaching distances up to 100 km, slightly affected nearby villages as Tuxpan, Tonila, Zapotlán, Cuauhtemoc, Comala, Zapotitlan de Vadillo and Toliman. During the 2005 this volcano has had an intense effusive-explosive activity, similar to the one that took place during the period of 1890 through 1900. Intense pre-plinian eruption in January 20, 1913, generated little economic losses in the lower parts of the volcano due to low population density and low socio-economic activities at the time. Shows the updating of the volcanic hazard maps published in 2001, where we identify whit SPOT satellite imagery and Google Earth, change in the land use on the slope of volcano, the expansion of the agricultural frontier on the east and southeast sides of the Colima volcano, the population inhabiting the area is approximately 517,000 people, and growing at an annual rate of 4.77%, also the region that has shown an increased in the vulnerability for the development of economic activities, supported by the construction of highways, natural gas pipelines and electrical infrastructure that connect to the Port of Manzanillo to Guadalajara city. The update the hazard maps are: a) Exclusion areas and moderate hazard for explosive events

  20. Tonantzintla's Observatory Astronomy Teaching Laboratory project

    Science.gov (United States)

    Garfias, F.; Bernal, A.; Martínez, L. A.; Sánchez, L.; Hernández, H.; Langarica, R.; Iriarte, A.; Peña, J. H.; Tinoco, S.; Ángeles, F.

    2008-07-01

    In the last two years the National Observatory at Tonantzintla Puebla, México (OAN Tonantzintla), has been undergoing several facilities upgrades in order to bring to the observatory suitable conditions to operate as a modern Observational Astronomy Teaching Laboratory. In this paper, we present the management, requirement definition and project advances. We made a quantitative diagnosis about of the functionality of the Tonantzintla Observatory (mainly based in the 1m f/15 telescope) to take aim to educational objectives. Through this project we are taking the steps to correct, to actualize and to optimize the observatory astronomical instrumentation according to modern techniques of observation. We present the design and the first actions in order to get a better and efficient use of the main astronomical instrumentation, as well as, the telescope itself, for the undergraduate, postgraduate levels Observacional Astronomy students and outreach publics programs for elementary school. The project includes the development of software and hardware components based in as a common framework for the project management. The Observatory is located at 150 km away from the headquarters at the Instituto de Astronomía, Universidad Nacional Autónoma de México (IAUNAM), and one of the goals is use this infrastructure for a Remote Observatory System.

  1. Telescopes in Education: the Little Thompson Observatory

    Science.gov (United States)

    Schweitzer, A. E.; Melsheimer, T. T.

    2003-12-01

    The Little Thompson Observatory is the first community-built observatory that is part of a high school and accessible to other schools remotely, via the Internet. This observatory is the second member of the Telescopes in Education (TIE) project. Construction of the building was done completely by volunteer labor, and first light occurred in May 1999. The observatory is located on the grounds of Berthoud High School in northern Colorado. We are grateful to have received an IDEAS grant to provide teacher training workshops for K-12 schools to make use of the observatory, including remote observing from classrooms. Students connect to the observatory over the Internet, and then receive the images back on their local computers. A committee of teachers and administrators from the Thompson School District selected these workshops to count towards Incentive Credits (movement on the salary schedule) because the course meets the criteria: "Learning must be directly transferable to the classroom with students and relate to standards, assessment and/or technology." Our program is also accredited by Colorado State University.

  2. An automated SO2 camera system for continuous, real-time monitoring of gas emissions from Kīlauea Volcano's summit Overlook Crater

    Science.gov (United States)

    Kern, Christoph; Sutton, Jeff; Elias, Tamar; Lee, Robert Lopaka; Kamibayashi, Kevan P.; Antolik, Loren; Werner, Cynthia A.

    2015-01-01

    SO2 camera systems allow rapid two-dimensional imaging of sulfur dioxide (SO2) emitted from volcanic vents. Here, we describe the development of an SO2 camera system specifically designed for semi-permanent field installation and continuous use. The integration of innovative but largely “off-the-shelf” components allowed us to assemble a robust and highly customizable instrument capable of continuous, long-term deployment at Kīlauea Volcano's summit Overlook Crater. Recorded imagery is telemetered to the USGS Hawaiian Volcano Observatory (HVO) where a novel automatic retrieval algorithm derives SO2 column densities and emission rates in real-time. Imagery and corresponding emission rates displayed in the HVO operations center and on the internal observatory website provide HVO staff with useful information for assessing the volcano's current activity. The ever-growing archive of continuous imagery and high-resolution emission rates in combination with continuous data from other monitoring techniques provides insight into shallow volcanic processes occurring at the Overlook Crater. An exemplary dataset from September 2013 is discussed in which a variation in the efficiency of shallow circulation and convection, the processes that transport volatile-rich magma to the surface of the summit lava lake, appears to have caused two distinctly different phases of lake activity and degassing. This first successful deployment of an SO2 camera for continuous, real-time volcano monitoring shows how this versatile technique might soon be adapted and applied to monitor SO2 degassing at other volcanoes around the world.

  3. "Route of astronomical observatories'' project: classical observatories from the Renaissance to the rise of astrophysics

    Science.gov (United States)

    Wolfschmidt, Gudrun

    2015-08-01

    Observatories offer a good possibility for serial transnational applications. A well-known example for a thematic programme is the Struve arc, already recognized as World Heritage.I will discuss what has been achieved and show examples, like the route of astronomical observatories or the transition from classical astronomy to modern astrophysics (La Plata, Hamburg, Nice, etc.), visible in the architecture, the choice of instruments, and the arrangement of the observatory buildings in an astronomy park. This corresponds to the main categories according to which the ``outstanding universal value'' (UNESCO criteria ii, iv and vi) of the observatories have been evaluated: historic, scientific, and aesthetic. This proposal is based on the criteria of a comparability of the observatories in terms of the urbanistic complex and the architecture, the scientific orientation, equipment of instruments, authenticity and integrity of the preserved state, as well as in terms of historic scientific relations and scientific contributions.Apart from these serial transnational applications one can also choose other groups like baroque or neo-classical observatories, solar physics observatories or a group of observatories equipped with the same kind of instruments and made by the same famous firm. I will also discuss why the implementation of the Astronomy and World Heritage Initiative is difficult and why there are problems to nominate observatories for election in the national Tentative Lists

  4. Virunga Volcanoes Supersite: a collaborative initiative to improve Geohazards Assessment and Monitoring of Active Volcanoes in a highly populated region

    Science.gov (United States)

    Balagizi, Charles M.; Mahinda, Celestin K.; Yalire, Mathieu M.; Ciraba, Honoré M.; Mavonga, Georges T.

    2017-04-01

    Reduction in the region. Furthermore, the large amount of expected scientific results will provide new insights on the understanding of the continental rift process, thus promoting the advance of scientific research. The supersites initiative promotes broad international scientific collaboration and open access to a variety of space- and ground-based data, and hence improves geophysical scientific research and Geohazards assessment in support of Disaster Risk Reduction. Presently, the Goma Volcano Observatory collects ground-based seismic, geochemical (SO2, CO2, Rn, temperature) and ground-deformation (GPS, EDM and Extensometry) data, which, together with remote and additional ground-based data that could be collected through the supersites network; may improve Geohazards assessment and monitoring in the Virunga region.

  5. Single Particle Characterization of Free Tropospheric Aerosols at the Pico Mountain Observatory over the North Atlantic

    Science.gov (United States)

    Mazzoleni, C.; China, S.; Scarnato, B. V.; Moffet, R.; OBrien, R. E.; Gilles, M. K.; Fialho, P. J.; Ampadu, M.; Kumar, S.; Dzepina, K.; Wright, K.; Sharma, N.; Zhang, B.; Owen, R. C.; Perlinger, J. A.; Jacques, H.; Helmig, D.; Dziobak, M.; Kramer, L. J.; Mazzoleni, L. R.

    2014-12-01

    Free tropospheric aerosols are being studied at the Pico Mountain Observatory, located near the top of the Pico volcano in the Azores, Portugal (38.47°N, 28.40°W, 2225m asl). Typically above the marine boundary layer in the summer, this is an ideal site to study aerosol transported over long distances across the Atlantic Ocean. Aerosols reaching the Observatory often originate from North America and sometimes from Africa and Europe. Aerosols instrumentation deployed at the site include: a) an optical particle counter, b) a 7-wavelength aethalometer to measure black carbon equivalent mass concentration, c) a 3-wavelength nephelometer to measure total and backward light scattering, d) four high volume samplers for aerosol chemical characterization, and e) a sequential aerosol sampler and a 4-stage impactor to collect particles on different substrates for microscopy analysis. The origin and transport pathways of the air masses sampled at the site are determined using FLEXible PARTicle (FLEXPART) dispersion modeling retroplume analysis. Single particle morphology and mixing states were determined using electron microscopy, energy dispersive X-ray spectroscopy, and scanning transmission x-ray microscopy. This study provides an overview of different types of aerosol collected at Pico Mountain Observatory. We investigated morphology and mixing of various types of particles, including dust, soot, salt and organic particles transported to the Observatory. Soot particles were often mixed/coated with other material and exhibited very compact shape. Dust particles were often mixed with sulfur containing species. We also observed dust particles that were mixed with coated soot particles. During some events, we observed soot and sulfate aerosol trapped within organic matter. The results of this study have implications on how aerosol particles and their internal mixing can be represented in numerical models for remote regions of the free troposphere.

  6. Tracking in Real-Time Pyroclastic Flows at Soufriere Hills Volcano, Montserrat, by infrasonic array.

    Science.gov (United States)

    Ripepe, M.; de Angelis, S.; Lacanna, G.; Poggi, P.; Williams, C.

    2008-12-01

    Active volcanoes produce infrasonic airwaves, which provide valuable insight into the eruption dynamics and the level of volcanic activity. On open conduit volcanoes, infrasound can be used to monitor the gas overpressure in the magma and the degassing rate of active volcanic vents. On volcanoes characterized by dome growth, infrasound can also be generated by non-explosive sources related to dome collapses and pyroclastic flows. In March 2008, the Department of Earth Science (DST) of Firenze (Italy) in cooperation with Montserrat Volcano Observatory (MVO) has installed a small-aperture infrasonic array at a distance of ~3000 m from the dome of the Soufriere Hill Volcano (SHV). The array has an aperture of 200 m and a "star" geometry, with 3 satellite stations at 100 m distance from the receiving central station. Each element of the array is linked to the receiver station by fiber optics cable, and the signal is acquired with a resolution of 16 bits at a rate of 50 samples/sec. The data collected by the array are sent via a radio modem link to the MVO offices, on Montserrat, where they are archived and processed in real-time. Real-time location of infrasonic events are obtained and displayed on computer monitors for use in monitoring of volcanic activity. After a period of very low levels of activity, starting from the end of May 2008, SHV has produced several small explosions without any short-term precursory sign. Some of these events have generated ash plumes reaching up to a few thousands of meters above the sea level, and were accompanied by moderate-to-large size pyroclastic flows that descended the western flanks of the volcanic edifice. The array was able to detect and locate in real-time the clear infrasound associated both with the explosions and the pyroclastic flows. In the latter case, the array estimated the speed and the direction of the flux revealing the presence of several pulses within the same flow. The variable azimuth of the signal during the

  7. Explosive eruptions at Bezymianny Volcano (Kamchatka, Russia) from 2000-2009: warning system, prediction and risk assessment

    Science.gov (United States)

    Senyukov, S.

    2010-12-01

    for population centers, were released to the Kamchatka Branch of the Russian Advisory Council. The copies of these documents were sent to participants of the KVERT (Kamchatka Volcano Eruption Response Team) project, uniting scientists Alaska Volcano Observatory, Institute of Volcanology and Seismology and KBGS. One explosive eruption was missed and only one false prediction (due to incorrect data) was made during this time period. Seismic precursors of sixteen explosive eruptions of Bezymianny were investigated using seismic data from both Bezymianny and nearby Kluchevskoy Volcano to improve risk assessment. It was determined that the successful prediction of a Bezymianny eruption depends strongly on the activity at Kluchevskoy.

  8. Space Radar Image of Colombian Volcano

    Science.gov (United States)

    1999-01-01

    This is a radar image of a little known volcano in northern Colombia. The image was acquired on orbit 80 of space shuttle Endeavour on April 14, 1994, by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR). The volcano near the center of the image is located at 5.6 degrees north latitude, 75.0 degrees west longitude, about 100 kilometers (65 miles) southeast of Medellin, Colombia. The conspicuous dark spot is a lake at the bottom of an approximately 3-kilometer-wide (1.9-mile) volcanic collapse depression or caldera. A cone-shaped peak on the bottom left (northeast rim) of the caldera appears to have been the source for a flow of material into the caldera. This is the northern-most known volcano in South America and because of its youthful appearance, should be considered dormant rather than extinct. The volcano's existence confirms a fracture zone proposed in 1985 as the northern boundary of volcanism in the Andes. The SIR-C/X-SAR image reveals another, older caldera further south in Colombia, along another proposed fracture zone. Although relatively conspicuous, these volcanoes have escaped widespread recognition because of frequent cloud cover that hinders remote sensing imaging in visible wavelengths. Four separate volcanoes in the Northern Andes nations ofColombia and Ecuador have been active during the last 10 years, killing more than 25,000 people, including scientists who were monitoring the volcanic activity. Detection and monitoring of volcanoes from space provides a safe way to investigate volcanism. The recognition of previously unknown volcanoes is important for hazard evaluations because a number of major eruptions this century have occurred at mountains that were not previously recognized as volcanoes. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of

  9. A volcano-seismic event spotting system for the use in rapid response systems

    Science.gov (United States)

    Hammer, Conny; Ohrnberger, Matthias

    2010-05-01

    The classification of seismic signals of volcanic origin is an important task in monitoring active volcanoes. The number and size of certain types of seismic events usually increase before periods of volcanic crisis and can be used to quantify the volcanic activity. Due to the advantage of providing consistent, objective and time-invariant results automatic classification systems are preferred. Most automatic classification systems are trained in a supervised fashion from a sufficiently large pre-classified data set. The setup of an automatic classification system thus requires the pre-existence of these training data. For a rapid volcano-response team, however, the situation is often different. In the worst case, no prior observations exist (e.g. re-awakening of a dormant volcano). More frequently, archive data exist for a particular observatory network, but no record of seismicity for a high volcanic activity level exists and new seismicity patterns occur. Usually, the networks are additionally sparse and new equipment will be installed for better surveillance during the actual crisis. For the new recording sites again no prior example data is available. Finally, due to the imminent crisis there might be no time for the time-consuming and tedious process of preparing a training data set. For all these reasons a classification system which allows a "learning-while-recording" approach would be very advantageous for use in rapid response systems. Within this study, we show a novel seismic event spotting approach in order to reduce the dependency on the existence of previously acquired data bases and classification schemes. One main goal is therefore to provide the observatory staff with a robust event classification system based on a minimum number of reference waveforms and thus allowing for a fast build-up of a volcanic signal classification scheme as early as interesting events have been identified. For implementation issues we make use of the Hidden Markov

  10. Common processes at unique volcanoes – a volcanological conundrum

    Directory of Open Access Journals (Sweden)

    Katharine eCashman

    2014-11-01

    Full Text Available An emerging challenge in modern volcanology is the apparent contradiction between the perception that every volcano is unique, and classification systems based on commonalities among volcano morphology and eruptive style. On the one hand, detailed studies of individual volcanoes show that a single volcano often exhibits similar patterns of behaviour over multiple eruptive episodes; this observation has led to the idea that each volcano has its own distinctive pattern of behaviour (or personality. In contrast, volcano classification schemes define eruption styles referenced to type volcanoes (e.g. Plinian, Strombolian, Vulcanian; this approach implicitly assumes that common processes underpin volcanic activity and can be used to predict the nature, extent and ensuing hazards of individual volcanoes. Actual volcanic eruptions, however, often include multiple styles, and type volcanoes may experience atypical eruptions (e.g., violent explosive eruptions of Kilauea, Hawaii1. The volcanological community is thus left with a fundamental conundrum that pits the uniqueness of individual volcanic systems against generalization of common processes. Addressing this challenge represents a major challenge to volcano research.

  11. Augustine Volcano, Cook Inlet, Alaska (January 12, 2006)

    Science.gov (United States)

    2006-01-01

    Since last spring, the U.S. Geological Survey's Alaska Volcano Observatory (AVO) has detected increasing volcanic unrest at Augustine Volcano in Cook Inlet, Alaska near Anchorage. Based on all available monitoring data, AVO regards that an eruption similar to 1976 and 1986 is the most probable outcome. During January, activity has been episodic, and characterized by emission of steam and ash plumes, rising to altitudes in excess of 9,000 m (30,000 ft), and posing hazards to aircraft in the vicinity. An ASTER image was acquired at 12:42 AST on January 12, 2006, during an eruptive phase of Augustine. The perspective rendition shows the eruption plume derived from the ASTER image data. ASTER's stereo viewing capability was used to calculate the 3-dimensional topography of the eruption cloud as it was blown to the south by prevailing winds. From a maximum height of 3060 m (9950 ft), the plume cooled and its top descended to 1900 m (6175 ft). The perspective view shows the ASTER data draped over the plume top topography, combined with a base image acquired in 2000 by the Landsat satellite, that is itself draped over ground elevation data from the Shuttle Radar Topography Mission. The topographic relief has been increased 1.5 times for this illustration. Comparison of the ASTER plume topography data with ash dispersal models and weather radar data will allow the National Weather Service to validate and improve such models. These models are used to forecast volcanic ash plume trajectories and provide hazard alerts and warnings to aircraft in the Alaska region. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with

  12. 195-Year History of Mykolayiv Observatory: Events and People

    Directory of Open Access Journals (Sweden)

    Shulga, O.V.

    2017-01-01

    Full Text Available The basic stages of the history of the Mykolaiv Astronomical Observatory are shown. The main results of the Observatory activities are presented by the catalogs of star positions, major and minor planets in the Solar system, space objects in the Earth orbit. The information on the qualitative and quantitative structure of the Observatory, cooperation with the observatories of Ukraine and foreign countries as well as major projects carried out in the Observatory is provided.

  13. 激光二极管阵列端面抽运混合腔Nd:YVO4板条1064nm和1342nm激光特性研究%Laser Diode Stack End-Pumped Nd: YVO4 Slab Laser with Hybrid Resonator at 1064 nm and 1342 nm

    Institute of Scientific and Technical Information of China (English)

    张恒利; 闫莹; 刘洋; 李静; 辛建国

    2010-01-01

    利用激光二极管(LD)阵列端面抽运Nd:YVO4板条晶体,结合稳定-非稳混合腔,实现了高功率、高效率、高光束质量的1064 nm和1342 nm激光输出.板条Nd:YVO4晶体掺杂原子数分数为0.3%,尺寸12 mm×10 mm×1 mm,a轴切割,c轴平行于12 mm方向.采用稳定一正支共焦非稳腔,在抽运功率为265 W时,得到了123 W的1064 nm连续激光输出,光-光转换效率和斜效率分别为46.4%和52.4%;在输出功率约为100 W时测得稳腔和非稳腔两个方向的M2因子均为1.3,输出功率不稳定性小于1%.采用稳定-负支共焦非稳腔,在抽运功率为139.5 W时,得到35.4 W的1342 nm激光输出,光-光转换效率为25.4%,在稳腔方向光束质量为M2=1.23;在非稳腔方向光束质量为M2=1.14.

  14. Natural hazards and risk reduction in Hawai'i: Chapter 10 in Characteristics of Hawaiian volcanoes

    Science.gov (United States)

    Kauahikaua, James P.; Tilling, Robert I.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Significant progress has been made over the past century in understanding, characterizing, and communicating the societal risks posed by volcanic, earthquake, and tsunami hazards in Hawai‘i. The work of the Hawaiian Volcano Observatory (HVO), with a century-long commitment to serving the public with credible hazards information, contributed substantially to this global progress. Thomas A. Jaggar, Jr., HVO’s founder, advocated that a scientific approach to understanding these hazards would result in strategies to mitigate their damaging effects. The resultant hazard-reduction methods range from prediction of eruptions and tsunamis, thereby providing early warnings for timely evacuation (if needed), to diversion of lava flows away from high-value infrastructure, such as hospitals. In addition to long-term volcano monitoring and multifaceted studies to better understand eruptive and seismic phenomena, HVO has continually and effectively communicated—through its publications, Web site, and public education/outreach programs—hazards information to emergency-management authorities, news media, and the public.

  15. Parallel System Architecture (PSA): An efficient approach for automatic recognition of volcano-seismic events

    Science.gov (United States)

    Cortés, Guillermo; García, Luz; Álvarez, Isaac; Benítez, Carmen; de la Torre, Ángel; Ibáñez, Jesús

    2014-02-01

    Automatic recognition of volcano-seismic events is becoming one of the most demanded features in the early warning area at continuous monitoring facilities. While human-driven cataloguing is time-consuming and often an unreliable task, an appropriate machine framework allows expert technicians to focus only on result analysis and decision-making. This work presents an alternative to serial architectures used in classic recognition systems introducing a parallel implementation of the whole process: configuration, feature extraction, feature selection and classification stages are independently carried out for each type of events in order to exploit the intrinsic properties of each signal class. The system uses Gaussian Mixture Models (GMMs) to classify the database recorded at Deception Volcano Island (Antarctica) obtaining a baseline recognition rate of 84% with a cepstral-based waveform parameterization in the serial architecture. The parallel approach increases the results to close to 92% using mixture-based parameterization vectors or up to 91% when the vector size is reduced by 19% via the Discriminative Feature Selection (DFS) algorithm. Besides the result improvement, the parallel architecture represents a major step in terms of flexibility and reliability thanks to the class-focused analysis, providing an efficient tool for monitoring observatories which require real-time solutions.

  16. A multipurpose camera system for monitoring Kīlauea Volcano, Hawai'i

    Science.gov (United States)

    Patrick, Matthew R.; Orr, Tim R.; Lee, Lopaka; Moniz, Cyril J.

    2015-01-01

    We describe a low-cost, compact multipurpose camera system designed for field deployment at active volcanoes that can be used either as a webcam (transmitting images back to an observatory in real-time) or as a time-lapse camera system (storing images onto the camera system for periodic retrieval during field visits). The system also has the capability to acquire high-definition video. The camera system uses a Raspberry Pi single-board computer and a 5-megapixel low-light (near-infrared sensitive) camera, as well as a small Global Positioning System (GPS) module to ensure accurate time-stamping of images. Custom Python scripts control the webcam and GPS unit and handle data management. The inexpensive nature of the system allows it to be installed at hazardous sites where it might be lost. Another major advantage of this camera system is that it provides accurate internal timing (independent of network connection) and, because a full Linux operating system and the Python programming language are available on the camera system itself, it has the versatility to be configured for the specific needs of the user. We describe example deployments of the camera at Kīlauea Volcano, Hawai‘i, to monitor ongoing summit lava lake activity. 

  17. Time-lapse characterization of hydrothermal seawater and microbial interactions with basaltic tephra at Surtsey Volcano

    Science.gov (United States)

    Jackson, M. D.; Gudmundsson, M. T.; Bach, W.; Cappelletti, P.; Coleman, N. J.; Ivarsson, M.; Jónasson, K.; Jørgensen, S. L.; Marteinsson, V.; McPhie, J.; Moore, J. G.; Nielson, D.; Rhodes, J. M.; Rispoli, C.; Schiffman, P.; Stefánsson, A.; Türke, A.; Vanorio, T.; Weisenberger, T. B.; White, J. D. L.; Zierenberg, R.; Zimanowski, B.

    2015-12-01

    A new International Continental Drilling Program (ICDP) project will drill through the 50-year-old edifice of Surtsey Volcano, the youngest of the Vestmannaeyjar Islands along the south coast of Iceland, to perform interdisciplinary time-lapse investigations of hydrothermal and microbial interactions with basaltic tephra. The volcano, created in 1963-1967 by submarine and subaerial basaltic eruptions, was first drilled in 1979. In October 2014, a workshop funded by the ICDP convened 24 scientists from 10 countries for 3 and a half days on Heimaey Island to develop scientific objectives, site the drill holes, and organize logistical support. Representatives of the Surtsey Research Society and Environment Agency of Iceland also participated. Scientific themes focus on further determinations of the structure and eruptive processes of the type locality of Surtseyan volcanism, descriptions of changes in fluid geochemistry and microbial colonization of the subterrestrial deposits since drilling 35 years ago, and monitoring the evolution of hydrothermal and biological processes within the tephra deposits far into the future through the installation of a Surtsey subsurface observatory. The tephra deposits provide a geologic analog for developing specialty concretes with pyroclastic rock and evaluating their long-term performance under diverse hydrothermal conditions. Abstracts of research projects are posted at http://surtsey.icdp-online.org.

  18. Darwin's triggering mechanism of volcano eruptions

    Science.gov (United States)

    Galiev, Shamil

    2010-05-01

    Charles Darwin wrote that ‘… the elevation of many hundred square miles of territory near Concepcion is part of the same phenomenon, with that splashing up, if I may so call it, of volcanic matter through the orifices in the Cordillera at the moment of the shock;…' and ‘…a power, I may remark, which acts in paroxysmal upheavals like that of Concepcion, and in great volcanic eruptions,…'. Darwin reports that ‘…several of the great chimneys in the Cordillera of central Chile commenced a fresh period of activity ….' In particular, Darwin reported on four-simultaneous large eruptions from the following volcanoes: Robinson Crusoe, Minchinmavida, Cerro Yanteles and Peteroa (we cite the Darwin's sentences following his The Voyage of the Beagle and researchspace. auckland. ac. nz/handle/2292/4474). Let us consider these eruptions taking into account the volcano shape and the conduit. Three of the volcanoes (Minchinmavida (2404 m), Cerro Yanteles (2050 m), and Peteroa (3603 m)) are stratovolcanos and are formed of symmetrical cones with steep sides. Robinson Crusoe (922 m) is a shield volcano and is formed of a cone with gently sloping sides. They are not very active. We may surmise, that their vents had a sealing plug (vent fill) in 1835. All these volcanoes are conical. These common features are important for Darwin's triggering model, which is discussed below. The vent fill material, usually, has high level of porosity and a very low tensile strength and can easily be fragmented by tension waves. The action of a severe earthquake on the volcano base may be compared with a nuclear blast explosion of the base. It is known, that after a underground nuclear explosion the vertical motion and the surface fractures in a tope of mountains were observed. The same is related to the propagation of waves in conical elements. After the explosive load of the base. the tip may break and fly off at high velocity. Analogous phenomenon may be generated as a result of a

  19. A Benthic Invertebrate Survey of Jun Jaegyu Volcano: An active undersea volcano in Antarctic Sound, Antarctica

    Science.gov (United States)

    Quinones, G.; Brachfeld, S.; Gorring, M.; Prezant, R. S.; Domack, E.

    2005-12-01

    Jun Jaegyu volcano, an Antarctic submarine volcano, was dredged in May 2004 during cruise 04-04 of the RV Laurence M. Gould to determine rock, sediment composition and marine macroinvertebrate diversity. The objectives of this study are to examine the benthic assemblages and biodiversity present on a young volcano. The volcano is located on the continental shelf of the northeastern Antarctic Peninsula, where recent changes in surface temperature and ice shelf stability have been observed. This volcano was originally swath-mapped during cruise 01-07 of the Research Vessel-Ice Breaker Nathaniel B. Palmer. During LMG04-04 we also studied the volcano using a SCUD video camera, and performed temperature surveys along the flanks and crest. Both the video and the dredge indicate a seafloor surface heavily colonized by benthic organisms. Indications of fairly recent lava flows are given by the absence of marine life on regions of the volcano. The recovered dredge material was sieved, and a total of thirty-three invertebrates were extracted. The compilation of invertebrate community data can subsequently be compared to other benthic invertebrate studies conducted along the peninsula, which can determine the regional similarity of communities over time, their relationship to environmental change and health, if any, and their relationship to geologic processes in Antarctic Sound. Twenty-two rock samples, all slightly weathered and half bearing encrusted organisms, were also analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Except for one conglomerate sample, all are alkali basalts and share similar elemental compositions with fresh, unweathered samples from the volcano. Two of the encrusted basalt samples have significantly different compositions than the rest. We speculate this difference could be due to water loss during sample preparation, loss of organic carbon trapped within the vesicles of the samples and/or elemental uptake by the

  20. An international network of magnetic observatories

    Science.gov (United States)

    Love, Jeffrey J.; Chulliat, A.

    2013-01-01

    Since its formation in the late 1980s, the International Real-Time Magnetic Observatory Network (INTERMAGNET), a voluntary consortium of geophysical institutes from around the world, has promoted the operation of magnetic observatories according to modern standards [eg. Rasson, 2007]. INTERMAGNET institutes have cooperatively developed infrastructure for data exchange and management ads well as methods for data processing and checking. INTERMAGNET institute have also helped to expand global geomagnetic monitoring capacity, most notably by assisting magnetic observatory institutes in economically developing countries by working directly with local geophysicists. Today the INTERMAGNET consortium encompasses 57 institutes from 40 countries supporting 120 observatories (see Figures 1a and 1b). INTERMAGNET data record a wide variety of time series signals related to a host of different physical processes in the Earth's interiors and in the Earth's surrounding space environment [e.g., Love, 2008]. Observatory data have always had a diverse user community, and to meet evolving demand, INTERMAGNET has recently coordinated the introduction of several new data services.

  1. Fostering Student Awareness in Observatory STEM Careers

    Science.gov (United States)

    Keonaonaokalauae Acohido, Alexis Ann; Michaud, Peter D.; Gemini Public Information and Outreach Staff

    2016-01-01

    It takes more than scientists to run an observatory. Like most observatories, only about 20% of Gemini Observatory's staff is PhD. Scientists, but 100% of those scientists would not be able to do their jobs without the help of engineers, administrators, and other support staff that make things run smoothly. Gemini's Career Brochure was first published in 2014 to show that there are many different career paths available (especially in local host communities) at an astronomical observatory. Along with the printed career brochure, there are supplementary videos available on Gemini's website and Youtube pages that provide a more detailed and personal glimpse into the day-in-the-life of a wide assortment of Gemini employees. A weakness in most observatory's outreach programming point to the notion that students (and teachers) feel there is a disconnect between academics and where students would like to end up in their career future. This project is one of the ways Gemini addresses these concerns. During my 6-month internship at Gemini, I have updated the Career Brochure website conducted more in-depth interviews with Gemini staff to include as inserts with the brochure, and expanded the array of featured careers. The goal of my work is to provide readers with detailed and individualized employee career paths to show; 1) that there are many ways to establish a career in the STEM fields, and 2), that the STEM fields are vastly diverse.

  2. Maintenance management at La Silla Paranal Observatory

    Science.gov (United States)

    Montano, Nelson

    2008-07-01

    From the beginning of the VLT project, the European Southern Observatory (ESO) considered the application of a competent maintenance strategy a fundamental aspect for future operations of the Paranal Observatory. For that purpose, a special maintenance philosophy was developed during the project stage and applied during the initial years of operations. The merging of the La Silla and Paranal Observatories in 2005 added a new managerial challenge to the regular operational requirements (high availability and reliability) which motivated ESO Management to develop a stronger strategy for the operations of the new merged Observatory. Part of the new strategy considered the creation of a dedicated department for the management of all maintenance activities, separating this support from the traditional scheme where the Engineering Department had the responsibility for the entire technical support to operations. In order to keep a competent level of maintenance operations for the new unified Observatory, the La Silla Paranal (LSP) Maintenance Department has been using a well known maintenance management model used in various industrial applications as a guide. Today the operations of the Maintenance Department are concentrated on developing and implementing practices regarding concepts such as Maintenance Tactics, Planning, Data Management, Performance Indicators and Material Management. In addition to that, advances related to Reliability Analysis been taken in order to reach a superior level of excellence. The results achieved by the LSP Maintenance Department are reflected in a reduced rate of functional failures, allowing uninterrupted operations of the Observation sites.

  3. The Pu'u 'O'o-Kupaianaha Eruption of Kilauea Volcano, Hawaii: The First 20 Years

    Science.gov (United States)

    Heliker, Christina C.; Swanson, Donald A.; Takahashi, Taeko Jane

    2003-01-01

    The Pu'u 'O'o-Kupaianaha eruption started on January 3, 1983. The ensuing 20-year period of nearly continuous eruption is the longest at Kilauea Volcano since the famous lava-lake activity of the 19th century. No rift-zone eruption in more than 600 years even comes close to matching the duration and volume of activity of these past two decades. Fortunately, such a landmark event came during a period of remarkable technological advancements in volcano monitoring. When the eruption began, the Global Positioning System (GPS) and the Geographic Information System (GIS) were but glimmers on the horizon, broadband seismology was in its infancy, and the correlation spectrometer (COSPEC), used to measure SO2 flux, was still very young. Now, all of these techniques are employed on a daily basis to track the ongoing eruption and construct models about its behavior. The 12 chapters in this volume, written by present or past Hawaiian Volcano Observatory staff members and close collaborators, celebrate the growth of understanding that has resulted from research during the past 20 years of Kilauea's eruption. The chapters range widely in emphasis, subject matter, and scope, but all present new concepts or important modifications of previous ideas - in some cases, ideas long held and cherished.

  4. Intermediate-Term Declines in Seismicity at Mt. Wrangell and Mt. Veniaminof Volcanoes, Alaska, Following the November 3, 2002 Mw 7.9 Denali Fault Earthquake

    Science.gov (United States)

    Sanchez, J. J.; McNutt, S. R.

    2003-12-01

    On November 3, 2002 a Mw 7.9 earthquake ruptured segments of the Denali Fault and adjacent faults in interior Alaska providing a unique opportunity to look for intermediate-term (days to weeks) responses of Alaskan volcanoes to shaking from a large regional earthquake. The Alaska Volcano Observatory (AVO) monitors 24 volcanoes with seismograph networks. We examined one station per volcano, generally the closest to the vent (typically within 5 km) unless noise, or other factors made the data unusable. Data were digitally filtered between 0.8 and 5 Hz to enhance the signal-to-noise ratio. Data for the period four weeks before to four weeks after the Mw 7.9 earthquake were then plotted at a standard scale used for AVO routine monitoring. Mt. Veniaminof volcano, which has had recent mild eruptions and a rate of ten earthquakes per day on station VNNF, suffered a drop in seismicity by a factor of two after the earthquake; this lasted for 15 days. Wrangell, the closest volcano to the epicenter, had a background rate of about 16 earthquakes per day. Data from station WANC could not be measured for 3 days after the Mw 7.9 earthquake because the large number and size of aftershocks impeded identification of local earthquakes. For the following 30 days, however, its seismicity rate dropped by a factor of two. Seismicity then remained low for an additional 4 months at Wrangell, whereas that at Veniaminof returned to normal within weeks. The seismicity at both Mt. Veniaminof and Mt. Wrangell is dominated by low-frequency volcanic events. The detection thresholds for both seismograph networks are low and stations VNNF and WANC operated normally during the time of our study, thus we infer that the changes in seismicity may be related to the earthquake. It is known that Wrangell increased its heat output after the Mw 9.2 Alaska earthquake of 1964 and again after the Ms 7.1 St.Elias earthquake of 1979. The other volcanoes showed no changes in seismicity that can be attributable to

  5. Voluminous submarine lava flows from Hawaiian volcanoes

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, R.T.; Moore, J.G.; Lipman, P.W.; Belderson, R.H.

    1988-05-01

    The GLORIA long-range sonar imaging system has revealed fields of large lava flows in the Hawaiian Trough east and south of Hawaii in water as deep as 5.5 km. Flows in the most extensive field (110 km long) have erupted from the deep submarine segment of Kilauea's east rift zone. Other flows have been erupted from Loihi and Mauna Loa. This discovery confirms a suspicion, long held from subaerial studies, that voluminous submarine flows are erupted from Hawaiian volcanoes, and it supports an inference that summit calderas repeatedly collapse and fill at intervals of centuries to millenia owing to voluminous eruptions. These extensive flows differ greatly in form from pillow lavas found previously along shallower segments of the rift zones; therefore, revision of concepts of volcano stratigraphy and structure may be required.

  6. Vulcan's fury: Man against the volcano

    Science.gov (United States)

    Varekamp, Johan C.

    I read this book on an 11-hour flight back from a field trip in the Andes, where I got first-hand insight into how people live with a volcano that now and then explodes. Appropriate reading, I felt, especially as the fascination of the human world with volcanoes and eruptive disasters is indeed long standing. This book is a recent addition to a list of titles in this genre (e.g., the new book by Sigurdsson to be reviewed in Eos shortly). The scope of the book is summarized in the introductory sentence of the preface: “This book is about an unequal contest. It describes human reactions to volcanic eruptions.” This is the perspective of the book's descriptions of 16 large and not-so-large eruptions over the last two millennia.

  7. On the morphometry of terrestrial shield volcanoes

    Science.gov (United States)

    Grosse, Pablo; Kervyn, Matthieu

    2016-04-01

    Shield volcanoes are described as low angle edifices that have convex up topographic profiles and are built primarily by the accumulation of lava flows. This generic view of shields' morphology is based on a limited number of monogenetic shields from Iceland and Mexico, and a small set of large oceanic islands (Hawaii, Galapagos). Here, the morphometry of over 150 monogenetic and polygenetic shield volcanoes, identified inthe Global Volcanism Network database, are analysed quantitatively from 90-meter resolution DEMs using the MORVOLC algorithm. An additional set of 20 volcanoes identified as stratovolcanoes but having low slopes and being dominantly built up by accumulation of lava flows are documented for comparison. Results show that there is a large variation in shield size (volumes range from 0.1 to >1000 km3), profile shape (height/basal width ratios range from 0.01 to 0.1), flank slope gradients, elongation and summit truncation. Correlation and principal component analysis of the obtained quantitative database enables to identify 4 key morphometric descriptors: size, steepness, plan shape and truncation. Using these descriptors through clustering analysis, a new classification scheme is proposed. It highlights the control of the magma feeding system - either central, along a linear structure, or spatially diffuse - on the resulting shield volcano morphology. Genetic relationships and evolutionary trends between contrasted morphological end-members can be highlighted within this new scheme. Additional findings are that the Galapagos-type morphology with a central deep caldera and steep upper flanks are characteristic of other shields. A series of large oceanic shields have slopes systematically much steeper than the low gradients (<4-8°) generally attributed to large Hawaiian-type shields. Finally, the continuum of morphologies from flat shields to steeper complex volcanic constructs considered as stratovolcanoes calls for a revision of this oversimplified

  8. Buried caldera of mauna kea volcano, hawaii.

    Science.gov (United States)

    Porter, S C

    1972-03-31

    An elliptical caldera (2.1 by 2.8 kilometers) at the summit of Mauna Kea volcano is inferred to lie buried beneath hawaiite lava flows and pyroclastic cones at an altitude of approximately 3850 meters. Stratigraphic relationships indicate that hawaiite eruptions began before a pre-Wisconsin period of ice-cap glaciation and that the crest of the mountain attained its present altitude and gross form during a glaciation of probable Early Wisconsin age.

  9. Publications of the Volcano Hazards Program 2014

    Science.gov (United States)

    Nathenson, Manuel

    2016-04-08

    The Volcano Hazards Program of the U.S. Geological Survey (USGS) is part of the Natural Hazards activity, as funded by Congressional appropriation. Investigations are carried out by the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute, University of Hawaiʻi Mānoa and Hilo, University of Utah, and University of Washington Geophysics Program. This report lists publications from all of these institutions.

  10. The Lowell Observatory Predoctoral Scholar Program

    Science.gov (United States)

    van Belle, Gerard; Prato, Lisa A.

    2016-01-01

    Lowell Observatory is pleased to solicit applications for our Predoctoral Scholar Fellowship Program. Now beginning its eighth year, this program is designed to provide unique research opportunities to graduate students in good standing, currently enrolled at Ph.D. granting institutions. Lowell staff research spans a wide range of topics, from astronomical instrumentation, to icy bodies in our solar system, exoplanet science, stellar populations, star formation, and dwarf galaxies. The Observatory's new 4.3 meter Discovery Channel Telescope has successfully begun science operations and we anticipate the commissioning of new instruments in 2015, making this a particularly exciting time in our history. Student research is expected to lead to a thesis dissertation appropriate for graduation at the doctoral level at the student's home institution. The Observatory provides competitive compensation and full benefits to student scholars. For more information, see http://www2.lowell.edu/rsch/predoc.php and links therein. Applications for Fall 2016 are due by May 1, 2016.

  11. The York College observatory outreach program

    Science.gov (United States)

    Paglione, T.; Spergel, M.

    The primary mission of the York College Observatory Outreach Program is to im- prove minority participation in space science and space science education. We aim to achieve this goal by developing an urban observatory in central Queens: the York Col- lege Observatory (YCO). We concentrate our efforts in three main areas: academics, outreach and research. Academically, we utilize astronomy?s popular appeal to at- tract and retain students and to enhance existing science courses. We have also created a minor in Astronomy at York College, and are active members of the New York City Space Science Research Alliance, which has developed a City University major in Space Science. Our outreach efforts aim to increase the awareness of the general public through workshops for high school teachers, curriculum development for high schools and public open nights at the YCO. Our research program utilizes the radio and optical capabilities of the YCO and collaborations with other institutions.

  12. Environmental effects on lunar astronomical observatories

    Science.gov (United States)

    Johnson, Stewart W.; Taylor, G. Jeffrey; Wetzel, John P.

    1992-01-01

    The Moon offers a stable platform with excellent seeing conditions for astronomical observations. Some troublesome aspects of the lunar environment will need to be overcome to realize the full potential of the Moon as an observatory site. Mitigation of negative effects of vacuum, thermal radiation, dust, and micrometeorite impact is feasible with careful engineering and operational planning. Shields against impact, dust, and solar radiation need to be developed. Means of restoring degraded surfaces are probably essential for optical and thermal control surfaces deployed in long-lifetime lunar facilities. Precursor missions should be planned to validate and enhance the understanding of the lunar environment (e.g., dust behavior without and with human presence) and to determine environmental effects on surfaces and components. Precursor missions should generate data useful in establishing keepout zones around observatory facilities where rocket launches and landings, mining, and vehicular traffic could be detrimental to observatory operation.

  13. Noise in raw data from magnetic observatories

    Directory of Open Access Journals (Sweden)

    S. Y. Khomutov

    2017-09-01

    Full Text Available In spite of significant progress in the development of new devices for magnetic measurements, mathematical and computational technologies for data processing and means of communication, the quality of magnetic data accessible through the data centres (for example, World Data Centres or INTERMAGNET still largely depends on the actual conditions in which observation of the Earth's magnetic field is performed at observatories. Processing of raw data of magnetic measurements by observatory staff plays an important role. It includes effective identification of noise and elimination of its influence on final data. In this paper, on the basis of the experience gained during long-term magnetic monitoring carried out at the observatories of IKIR FEB RAS (Russia and CSIR-NGRI (India, we present a review of methods commonly encountered in actual practice for noise identification and the possibility of reducing noise influence.

  14. Noise in raw data from magnetic observatories

    Science.gov (United States)

    Khomutov, Sergey Y.; Mandrikova, Oksana V.; Budilova, Ekaterina A.; Arora, Kusumita; Manjula, Lingala

    2017-09-01

    In spite of significant progress in the development of new devices for magnetic measurements, mathematical and computational technologies for data processing and means of communication, the quality of magnetic data accessible through the data centres (for example, World Data Centres or INTERMAGNET) still largely depends on the actual conditions in which observation of the Earth's magnetic field is performed at observatories. Processing of raw data of magnetic measurements by observatory staff plays an important role. It includes effective identification of noise and elimination of its influence on final data. In this paper, on the basis of the experience gained during long-term magnetic monitoring carried out at the observatories of IKIR FEB RAS (Russia) and CSIR-NGRI (India), we present a review of methods commonly encountered in actual practice for noise identification and the possibility of reducing noise influence.

  15. Developing an astronomical observatory in Paraguay

    Science.gov (United States)

    Troche-Boggino, Alexis E.

    Background: Paraguay has some heritage from the astronomy of the Guarani Indians. Buenaventura Suarez S.J. was a pioneer astronomer in the country in the XVIII century. He built various astronomical instruments and imported others from England. He observed eclipses of Jupiter's satellites and of the Sun and Moon. He published his data in a book and through letters. The Japanese O.D.A. has collaborated in obtaining equipment and advised their government to assist Paraguay in building an astronomical observatory, constructing a moving-roof observatory and training astronomers as observatory operators. Future: An astronomical center is on the horizon and some possible fields of research are being considered. Goal: To improve education at all possible levels by not only observing sky wonders, but also showing how instruments work and teaching about data and image processing, saving data and building a data base. Students must learn how a modern scientist works.

  16. Reengineering observatory operations for the time domain

    CERN Document Server

    Seaman, Robert L; Hessman, Frederic V

    2014-01-01

    Observatories are complex scientific and technical institutions serving diverse users and purposes. Their telescopes, instruments, software, and human resources engage in interwoven workflows over a broad range of timescales. These workflows have been tuned to be responsive to concepts of observatory operations that were applicable when various assets were commissioned, years or decades in the past. The astronomical community is entering an era of rapid change increasingly characterized by large time domain surveys, robotic telescopes and automated infrastructures, and - most significantly - of operating modes and scientific consortia that span our individual facilities, joining them into complex network entities. Observatories must adapt and numerous initiatives are in progress that focus on redesigning individual components out of the astronomical toolkit. New instrumentation is both more capable and more complex than ever, and even simple instruments may have powerful observation scripting capabilities. Re...

  17. Die Gerling Sternwarte (Gerling Astronomical Observatory)

    CERN Document Server

    Schrimpf, Andreas

    2015-01-01

    Christian Ludwig Gerling's 1817 appointment as Professor for Mathematics, Physics and Astronomy resulted in the foundation of the Mathematical and Physical Institute of the Philipps University. In 1838, Gerling moved onto new premises in the main building of the former D\\"ornberger Hof in Renthof Street where the Philipps University's astronomical observatory was installed in the upper part of the old tower in 1841. The most important device at that time was a transit instrument which served to measure the transit times of stars in the meridian. Precise alignment required the use of a meridian stone, an artificial point of reference exactly north of and at about four kilometers' distance from the observatory. The scientists observed planets and their moons, the asteroids that were only discovered at the beginning of the 19th century, and some fainter stars in order to improve stellar charts. The Gerling Observatory is the first place in Hesse, where positions of asteroids were read.

  18. Multinational History of Strasbourg Astronomical Observatory

    CERN Document Server

    Heck, André

    2005-01-01

    Strasbourg Astronomical Observatory is quite an interesting place for historians: several changes of nationality between France and Germany, high-profile scientists having been based there, big projects born or installed in its walls, and so on. Most of the documents circulating on the history of the Observatory and on related matters have however been so far poorly referenced, if at all. This made necessary the compilation of a volume such as this one, offering fully-documented historical facts and references on the first decades of the Observatory history, authored by both French and German specialists. The experts contributing to this book have done their best to write in a way understandable to readers not necessarily hyperspecialized in astronomy nor in the details of European history. After an introductory chapter by the Editor, contributions by Wolfschmidt and by Duerbeck respectively deal extensively with the German periods and review people and instrumentation, while another paper by Duerbeck is more...

  19. Metadata salad at the Cordoba Observatory

    CERN Document Server

    Lencinas, Verónica

    2016-01-01

    The Plate Archive of the Cordoba Observatory includes 20.000 photographs and spectra on glass plates dating from 1893 to 1983. This contribution describes the work performed since the plate archive was transferred to the Observatory Library in 2011. In 2014 an interdisciplinary team was assembled and a research grant from the National University of Cordoba was obtained with the objectives of preserving the glass plates and generate public access for astronomers and other audiences. The preservation work not only includes practical intervention to improve conservation conditions for the whole archive, but also a diagnose of the preservation conditions for the plates and identification of best practices for cleaning the plates. The access envisioned through digitization requires not only the scanning of all the plates, but also careful definition and provision of metadata. In this regard, each institutional level involved -in this case: archive, library, astronomical observatory and public university - demands ...

  20. Hanohano:A Deep Ocean Antineutrino Observatory

    CERN Document Server

    Batygov, M; Learned, J G; Matsuno, S; Pakvasa, S; Varner, G

    2008-01-01

    This paper presents the science potential of a deep ocean antineutrino observatory being developed at Hawaii and elsewhere. The observatory design allows for relocation from one site to another. Positioning the observaory some 60 km distant from a nuclear reactor complex enables preecision measurement of neutrino mixing parameters, leading to a determination of neutrino mass hierarchy and theta_13. At a mid-Pacific location, the observatory measures the flux of uranium and thorium decay series antineutrinos from earth's mantle and performs a sensitive search for a hypothetical natural fission reactor in earth's core. A subequent deployment at another mid-ocean location would test lateral homogeneity of uranium and thorium in earth's mantle. These measurements have significance for earth energy studies.