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Sample records for hardened volcanic soils

  1. Ibuprofen adsorption in four agricultural volcanic soils.

    PubMed

    Estevez, Esmeralda; Hernandez-Moreno, Jose Manuel; Fernandez-Vera, Juan Ramon; Palacios-Diaz, Maria Pino

    2014-01-15

    Ibuprofen (IB) is a high environmental risk drug and one of the most frequently prescribed in human medicine. Recently, IB has been detected in Gran Canaria in reclaimed water for irrigation and in groundwater. Adsorption was studied in four volcanic soils from three islands of the Canarian Archipelago. Once the biodegradation process has been excluded from the experimental conditions, a batch method was applied using initial concentrations of 1-5-10-20-50-100-200 mg L(-1) and two soil/water ratios (w/V): 1:5 (OECD, 2000) and 1:1. Non-linear and linearized Langmuir and Freundlich equations were well fitted. The wide IB range tested in our batch studies allowed us to measure experimental adsorption values close to the maximum adsorption capacity (S(max)) as estimated by Langmuir, making it possible thereby to validate the use of the Langmuir equation when there is a burst of contamination at high concentration. The distribution coefficient (Kd), S(max) and Retardation Factor (RF) varied from 0.04 to 0.5 kg L(-1), 4-200 mgk g(-1) and 1.2-1.9, respectively. The lowest S(max) and Kd values were found for the 1:1S/W ratio whereas most batch studies employ 1:5S/W ratios, thus obtaining higher adsorption parameters than when considering field conditions (1:1). Despite the high anion retention of andic soils, similar Kd and RF to those reported for other soils were obtained in 1:5, while high S(max) was found. Our results demonstrate that IB adsorption in volcanic areas responds not only to the soil properties commonly cited in adsorption studies, but also depends on andic properties, sorbent concentration and Dissolved Organic Carbon, the higher values of which are related to the lower Kd and S(max). The low RF and low detection frequency of the IB in groundwater suggests that a) reclaimed water irrigation is not the main source of IB, and b) the existence of some uncontrolled water disposal points in the zone.

  2. Volcanism and soil mercury on Mars - Consequences for terrestrial microorganisms

    NASA Technical Reports Server (NTRS)

    Siegel, B. Z.; Siegel, S. M.

    1978-01-01

    An earth-Mars depletion formula proposed by Anders and Owen for volatiles is used to calculate a range of putative Hg levels for Martian volcanic soils based upon analyzed samples from Hawaii. The range is about 50-150 microgram per kg. When applied either in conventional or special media (e.g., basalt powder), these levels of Hg are effective inhibitors of the growth of earth microorganisms. Taken together with other hostile chemical and physical factors, volcanic toxicants would appear to provide a further deterrent to the accidental establishment of terrestrial microbiota on Mars.

  3. Colonisation of freshly deposited volcanic tephra by soil fungi

    NASA Astrophysics Data System (ADS)

    Tarasenko, Inga; Opfergelt, Sophie; Stenuit, Benoît; Daily, Hélène; Bonneville, Steeve; Müller, Dirk; Delmelle, Pierre

    2016-04-01

    In active volcanic regions, soils are repeatedly exposed to eruption products, notably tephra emissions. Deposition of volcanic tephra on soil may modify water and gas exchanges between the soil surface and the atmosphere. Through chemical weathering, the silicate glass and mineral components of freshly deposited tephra act as a source of bioavailable potassium and phosphorus. In addition, opportunist fungi may be able to enhance access to these elements via physical and biochemical processes. Altogether, tephra deposition has the potential to affect biological activity and hence, nutrient cycling in the buried soil. Here we present the preliminary results of an ongoing investigation aimed at shedding light on the interaction of soil fungi with freshly deposited tephra. The study site (elevation - 1755 m a.s.l.) is a coniferous forest on the northeastern slope of Etna volcano, Sicily, which received about 20 cm of tephra in November 2013. Soil and tephra samples were collected in September 2014 and October 2015. A variety of biological, chemical and mineralogical analyses were carried out to determine fungal biomass, fungi species and tephra weathering stage. Colonisation of the fresh tephra by fungi is evidenced by the high fungal biomass measured in this material. DNA analyses further indicate that these fungi originate from the soil beneath the tephra layer. While chemical weathering of the tephra material has started, there is no clear indication that fungi colonisation is enhancing this process. We will continue to monitor fungi-tephra interaction on Etna during the next few years.

  4. Magnetic susceptibility properties of pesticide contaminated volcanic soil

    NASA Astrophysics Data System (ADS)

    Agustine, Eleonora; Fitriani, Dini; Safiuddin, La Ode; Tamuntuan, Gerald; Bijaksana, Satria

    2013-09-01

    Pesticides, unfortunately, are still widely used in many countries as way to eradicate agricultural pests. As they are being used continuously over a long period of time, they accumulate as residues in soils posing serious threats to the environment. In this study, we study the changes in magnetite-rich volcanic soils that were deliberately contaminated by pesticide. Such changes, in any, would be useful in the detection of pesticide residue in contaminated soils. Two different types of magnetically strong volcanic soil from the area near Lembang, West Java, Indonesia were used in this study where they were contaminated with varying concentrations of pesticide. The samples were then measured for magnetic susceptibility at two different frequencies. The measurements were then repeated after a period of three months. We found a reduction of magnetic susceptibility as well as a reduction in SP (superparamagnetic) grains proportion in contaminated soil. These might be caused by pesticide-induced magnetic dissolution as supported by SEM analyses. However the impact of pesticide concentration as well as exposure time on magnetic dissolution is still inconclusive.

  5. Volatile metal deposits on lunar soils: Relation to volcanism

    NASA Technical Reports Server (NTRS)

    Reed, G. W., Jr.; Allen, R. O., Jr.; Jovanovic, S.

    1977-01-01

    Parallel leaching and volatilization experiments conducted on lunar samples and similar experiments on sphalerite do not supply the information needed to resolve the question of the chemical nature of pb 204, Zn, Bi and Tl deposits on lunar soil surfaces. It is proposed that in Apollo 17 mare and terra soils and fractions of pb 204, Zn and Tl that are insoluble under mild, hot pH 5HNO3, leaching conditions and involatile at 600 C were originally surface deposits which became immobilized by migration into the silicate substrate or by chemisorption. Only Bi is predominantly indigenous. The implication is also that the soils over their respective times of evolution were exposed to heavy metal vapors or that an episodic exposure occurred after they had evolved. A sequence of events is proposed to account for orange 74220 and black 74001 glasses by lava fountaining and for soil 74241 as tephra from an explosive volcanic eruption.

  6. Disposal of domestic sludge and sludge ash on volcanic soils.

    PubMed

    Escudey, Mauricio; Förster, Juan E; Becerra, Juan P; Quinteros, Magdalena; Torres, Justo; Arancibia, Nicolas; Galindo, Gerardo; Chang, Andrew C

    2007-01-31

    Column leaching experiments were conducted to test the ability of Chilean volcanic soils in retaining the mineral constituents and metals in sewage sludge and sludge ash that were incorporated into the soils. Small or negligible amounts of the total content of Pb, Fe, Cr, Mn, Cd, and Zn (0 to <2%), and more significant amounts of mineral constituents such as Na (7-9%), Ca (7-13%), PO4 (4-10%), and SO4 (39-46%) in the sludge and sludge ash were readily soluble. When they were incorporated on the surface layer of the soils and leached with 12 pore volumes of water over a 3 month period of time, less than 0.1% of the total amount of heavy metals and PO4 in the sludge and sludge ash were collected in the drainage water. Cation exchange selectivity, specific anion adsorption and solubility are the processes that cause the reduction of leaching. The volcanic soils were capable of retaining the mineral constituents, P, and metals in applied sewage sludge and sludge ash and gradually released them as nutrients for plant growth.

  7. Prehistoric Agriculture and Soil Fertility on Lava Flows in Northern Arizona, USA: Results from the San Francisco Volcanic Field REU

    NASA Astrophysics Data System (ADS)

    Broadman, E.; Anderson, K. C.

    2013-12-01

    The San Francisco Volcanic Field in northern Arizona is home to ~600 cinder cones, the youngest of which is Sunset Crater (erupted ~AD 1100). This study documents trends in available phosphate and nitrate content with time, testing whether lowered soil pH from the addition of Sunset cinders increased soil fertility and became a factor in Anasazi agricultural success. Soil fertility is examined both before and after Sunset's eruption in soils of different ages that have developed from eolian deposition on top of lava flows. An increase in phosphate and nitrate levels following acidification would suggest that the presence of Sunset cinders brought the soils to the optimal pH for mobilization of these nutrients. The combined effects of the cinder layer retaining nutrients and water, wetter climates, and increases in phosphate and nitrate (both limiting nutrients for plant growth), would have contributed to Anasazi agricultural success after Sunset's eruption. Samples for this study were taken from eolian-derived soils of different ages atop lava flows in the San Francisco Volcanic Field. OSL data from these soils on Strawberry and SP Craters' lava flows yielded age estimates of ~12.3 ka (Strawberry) and ~32.7 ka (SP), on which a soil chronosequence was based. Results from the chronosequence supported these OSL ages, indicating that soils on the SP flow are older than those on the Strawberry flow. Field descriptions, Harden Development Indices, particle size analysis, and nutrient content analysis were used for this aspect of the project. An experimental acid wash method will be used to simulate the addition of Sunset's acidic cinders, and will yield data for phosphate and nitrate content after Sunset erupted. Preliminary results indicate that phosphate and nitrate accumulate in upper, eolian-derived horizons (Av, Bw) and in more deeply buried carbonate horizons (Bk). Higher concentrations of phosphate and nitrate were found in older (SP) soils than younger

  8. Genesis of petroduric and petrocalcic horizons in Latinamerica volcanic soils

    NASA Astrophysics Data System (ADS)

    Quantin, Paul

    2010-05-01

    Introduction. In Latinamerica, from Mexico to Chile, there are indurated volcanic soils horizons, named 'tepetate' in Mexico or cangahua in the Andes Mountains. Apart from original volcanic tuffs, these horizons were produced by pedogenesis: either through a former weathering of volcanic ash layers into fragic and later to petrocalcic horizons; or after a former soil formation through a second process of transformation from clayey volcanic soils to silicified petroduric horizons. This oral presentation will briefly deal with the formation of petroduric horizons in Mexico and petrocalcic horizon in Ecuador. Petroduric horizon genesis in Mexico. A soil climato-toposequence, near to Veracruz (Rossignol & Quantin, 1997), shows downwards an evolution from a ferralic Nitisol to a petroduric Durisol. A Durisol profile comports these successive horizons: at the top A and Eg, then columnar Btg-sim, laminar Bt-sim , prismatic Bsim, plinthite Cg, over andesite lava flow. Among its main features are especially recorded: clay mineralogy, microscopy and HRTEM. These data show: an increase in cristobalite at the expenses of 0.7 nm halloysite in Egsiltans, laminar Bt-sim, around or inside the columns or prisms of Btg-sim and Bsimhorizons. HRTEM (Elsass & al 2000) on ultra thin sections reveals an 'epigenesis' of clay sheets by amorphous silica, to form successively A-opal, Ct-opal and microcrystalline cristobalite. From these data and some groundwater chemical analyses, a scenario of duripan formation from a past clayey Nitisol is inferred: clay eluviation-illuviation process? alternate redoximorphy? clay degradation, Al leaching and Si accumulation, to form successively A-opal, Ct-opal and cristobalite. Petrocalcic horizon genesis in Ecuador. A soil climato-toposequence on pyroclastic flows, near to Bolivar in Ecuador (Quantin & Zebrowski, 1997), shows downwards the evolution from fragic-eutric-vitric Cambisols to petrocalcic-vitric Phaeozems, at the piedmont under semi

  9. Volatile metal deposits on lunar soils - Relation to volcanism

    NASA Technical Reports Server (NTRS)

    Reed, G. W., Jr.; Jovanovic, S.; Allen, R. O., Jr.

    1977-01-01

    Parallel leaching and volatilization experiments conducted on lunar samples and similar experiments on sphalerite do not supply the information needed to resolve the question of the chemical nature of Pb-204, Zn, Bi, and Tl deposits on lunar soil surfaces. It is proposed that in Apollo 17 mare and terra soils the fractions of Pb-204, Zn, and Tl that are insoluble under mild, hot pH 5 HNO3, leaching conditions and involatile at 600 C were originally surface deposits which became immobilized by migration into the silicate substrate or by chemisorption. Most of the Bi does not seem to be the result of such a deposit. The implication is also that the soils, over their respective times of evolution, were exposed to heavy metal vapors or that an episodic exposure occurred after they had evolved. A sequence of events is proposed to account for orange 74220 and black 74001 glasses by lava fountaining and for soil 74241 as tephra from an explosive volcanic eruption.

  10. Soil microbial communities as suitable bioindicators of trace metal pollution in agricultural volcanic soils

    NASA Astrophysics Data System (ADS)

    Parelho, Carolina; dos Santos Rodrigues, Armindo; do Carmo Barreto, Maria; Gonçalo Ferreira, Nuno; Garcia, Patrícia

    2015-04-01

    Summary: The biological, chemical and physical properties of soil confer unique characteristics that enhance or influence its overall biodiversity. The adaptive character of soil microbial communities (SMCs) to metal pollution allows discriminating soil health, since changes in microbial populations and activities may function as excellent indicators of soil pollutants. Volcanic soils are unique naturally fertile resources, extensively used for agricultural purposes and with particular physicochemical properties that may result in accumulation of toxic substances, such as trace metals (TM). In our previous works, we identified priority TM affecting agricultural Andosols under different agricultural land uses. Within this particular context, the objectives of this study were to (i) assess the effect of soil TM pollution in different agricultural systems (conventional, traditional and organic) on the following soil properties: microbial biomass carbon, basal soil respiration, metabolic quotient, enzymatic activities (β-glucosidase, acid phosphatase and dehydrogenase) and RNA to DNA ratio; and (ii) evaluate the impact of TM in the soil ecosystem using the integrated biomarker response (IBR) based on a set of biochemical responses of SMCs. This multi-biomarker approach will support the development of the "Trace Metal Footprint" for different agricultural land uses in volcanic soils. Methods: The study was conducted in S. Miguel Island (Azores, Portugal). Microbial biomass carbon was measured by chloroform-fumigation-incubation-assay (Vance et al., 1987). Basal respiration was determined by the Jenkinson & Powlson (1976) technique. Metabolic quotient was calculated as the ratio of basal respiration to microbial biomass C (Sparkling & West, 1988). The enzymatic activities of β-glucosidase and acid phosphatase were determined by the Dick et al. (1996) method and dehydrogenase activity by the Rossel et al. (1997) method. The RNA and DNA were co-extracted from the same

  11. Selective preservation of carbohydrates in volcanic ash soils

    NASA Astrophysics Data System (ADS)

    Kaal, J.; Buurman, P.; Nierop, K. G. J.; Piccolo, A.

    2009-04-01

    Volcanic soils (Andosols) are formed in volcanic ash and depending on environmental and climatic factors they develop to two main forms, either allophanic Andosols (dominated by amorphous minerals) or non-allophanic Andosols (dominated by Al/Fe organic matter complexes). Andosols contain the largest amounts of organic carbon of all mineral soil orders. In recent studies using analytical pyrolysis techniques on the soil organic matter (SOM) of allophanic soils from the Azores Islands (Portugal) there was no indication of preservation of plant-derived organic matter by allophane or Al3+, but the presence of large amounts of (microbial) polysaccharides and chitin suggested that secondary organic matter products were stabilized. In the present study we used 13C NMR to further explore the organic matter of the Andosols of the Azores, and applied a molecular mixing model (MMM; ascribing characteristic resonances to the main biocomponent classes carbohydrate, protein, lipid, lignin and char) to the quantified NMR spectra to allow for a quantitative comparison with pyrolysis-GC/MS. The dominance of O-alkyl and di-O-alkyl C in the NMR spectra and carbohydrate contribution to the predictions made by the MMM (50 ± 8%) confirms that the majority of the SOM can still be recognised as carbohydrate. The accumulation of secondary/microbial carbohydrates (and, to a lesser extent, secondary proteinaceous matter and chitins) is thus a key characteristic of these Andosols. NMR-MMM and pyrolysis-GC/MS were in rough agreement. However, NMR does not recognise chitin (N-containing carbohydrate-like material) and chitin-associated protein, nor can it be used to estimate the degree of degradation of the carbohydrates. Therefore, NMR (as applied here) has a very limited capacity for characterisation of the SOM particularly in the Andosols studied. On the other hand, large peaks from carboxylic and amidic functional groups detected by NMR were not observed by pyrolysis-GC/MS. It is therefore

  12. Geochemical and thermodynamic specificity of volcanic, hydrothermal and soil aerosols

    NASA Astrophysics Data System (ADS)

    Mukhamadiyarova, Renata V.; Alekhin, Yury V.; Karpov, Gennady A.; Makarova, Marina A.

    2010-05-01

    On the basis of element composition analyses results (ICP-MS) of hydrothermal and soil aerosols condensates, and also results of diagnostics of ultradisperse phases by means of power dispersive x-ray spectrometers features of phase and microelement composition of issue aerosols are discussed. Our researches of streams of polyelement issue from a soil cover and specificity of structure of volcanic aerosols have led us to a conclusion that is geochemistry area practically is not developed in the relation of microelement migration in lithosphere - atmosphere. Nanoaerosol particles (0,001 - 1 microns) submit to laws of gas dynamics and in fluid streams are steady enough. Experimental researches of polyelement emission streams from soils and low-temperature microelements migration have allowed to detail the reasons of rather high values of the soil issue. Complexity of authentic definition of forms of carrying over, structure and dispersion of particles of the gas phase emitting from a soil cover, is substantially connected with absence of methodically well-founded receptions of selection of water condensates, free from aerosol components, and methods of their reliable division in a stationary stage of processes of issue and condensation. Reception of the information on factors of distribution of metals between pore solutions, true gas complexes and mineral phases of soils, an estimation of a role gas electrophoresis at transition to molecular cluster and to water colloid aerosols (0.1 microns and less) have allowed us to clear up estimations of streams of soil issue. The differentiation of a multicomponent gas phase in near surface conditions at powerful Tolbachinsky eruption (PTE) 1975 - 1976 to formation of many native metals - gold, silver, copper, lead, bismuth, tungsten, numerous intermetallic compounds. In eruption ashes of Kamchatka volcanoes - Karymsky, Bezymyanny, Kljuchevskoy and Shivelutch we found not only iron oxides but also numerous grains of native

  13. Influences of Farming Management on Quality and Quantity of Soil Organic Matter in Volcanic Ash Soil

    NASA Astrophysics Data System (ADS)

    Yoshikawa, M.; Tanaka, H.; Matsumura, S.; Shimizu, T.; Zhang, M.

    2013-12-01

    Storage of soil organic matter (SOM) in terrestrial ecosystem plays a significant role in reducing carbon flux to the atmosphere and thus prevents the earth from global warming. In agricultural field, farming management, such as manure application and/or reduced tillage, are known to be effective methods to stimulate SOM storage. Volcanic ash soil, categorized into Andosols, is a major type of upland soil in Japan, and the soil contains relatively high concentration of SOM, meaning that volcanic ash soil can play an important role in carbon storage in Japan. To investigate the influences of farming management on quality and quantity of SOM, an empirical study was carried out in an upland soil field derived from volcanic ash. Surface soil samples were taken every three months from the field and fractionated physically and chemically. As for the physical fractionation, 53 μm sieving was performed. SOM in the samples were sorted into particulate organic matter (POM) denoting organic matter with particle size greater than 53 μm and less than 2 mm, and mineral-associated organic matter (MOM) denoting less than 53 μm. In addition, both POM and MOM were further fractionated chemically by extraction with pyrophosphate buffer solutions at three different pH levels. The fractionated organic matter as well as unfractionated SOM were analyzed and quantified for organic carbon, nitrogen content. This study induced the following results and findings. The manure and/or reduced tillage treatments can significantly increase the particulate organic carbon (POC) and all chemically fractionated POC contents. Especially, POC extracted with the buffer solution at pH4 (POCpH4) and the differences between POC and POC extracted with the buffer solution at pH10 (POC-POCpH10) have strong correlations with SOC, and manure application can effectively increase POC-POCpH10 fraction. The results indicate that these fractionated organic carbons would contribute storage of organic matter in

  14. Interannual variations of soil organic carbon fractions in unmanaged volcanic soils (Canary Islands, Spain)

    PubMed Central

    Armas-Herrera, Cecilia María; Mora, Juan Luis; Arbelo, Carmen Dolores; Rodríguez-Rodríguez, Antonio

    2012-01-01

    The stability over time of the organic C stocked in soils under undisturbed ecosystems is poorly studied, despite being suitable for detecting changes related to climate fluctuations and global warming. Volcanic soils often show high organic C contents due to the stabilization of organic matter by short-range ordered minerals or Al-humus complexes. We investigated the dynamics of different organic C fractions in volcanic soils of protected natural ecosystems of the Canary Islands (Spain) to evaluate the stability of their C pools. The study was carried out in 10 plots, including both undisturbed and formerly disturbed ecosystems, over two annual periods. C inputs to (litterfall) and outputs from (respiration) the soil, root C stocks (0–30 cm), soil organic C (SOC) fractions belonging to C pools with different degrees of biogeochemical stability –total oxidisable C (TOC), microbial biomass C (MBC), water soluble C (WSC), hot-water extractable C (HWC), humic C (HSC), – and total soil N (TN) (at 0–15 and 15–30 cm) were measured seasonally.A statistically significant interannual increase in CO2 emissions and a decrease in the SOC, mainly at the expense of the most labile organic forms, were observed, while the root C stocks and litterfall inputs remained relatively constant over the study period. The observed changes may reflect an initial increase in SOC resulting from low soil respiration rates due to drought during the first year of study. The soils of nearly mature ecosystems were more apparently affected by C losses, while those undergoing the process of active natural regeneration exhibited disguised C loss because of the C sequestration trend that is characteristic of progressive ecological succession. PMID:23145325

  15. Cemented Volcanic Soils, Martian Spectra and Implications for the Martian Climate

    NASA Astrophysics Data System (ADS)

    Bishop, J. L.; Schiffman, P.; Drief, A.; Southard, R. J.

    2004-03-01

    Cemented volcanic crusts are studied to learn about their composition, formation processes, and implications for climate interactions with the surface on Mars. Such carbonate, sulfate and opal crusts may be present in cemented soil units on Mars.

  16. Climatic controls on soil hydraulic properties along soil chronosequences on volcanic parent material

    NASA Astrophysics Data System (ADS)

    Beal, L. K.; Lohse, K. A.; Godsey, S.; Huber, D. P.

    2013-12-01

    . We observe that θ decreases with age, and α occurs at higher tensions. Soil horizons are developed dominantly on the cinder cones. These model estimates appear to match well with preliminary field measurements. Tropical climates enhance the weathering of basaltic parent material. The mean annual precipitation in the Hawaiian site is 2500 mm, and 310 mm at COTM. Accumulation of rainfall increases the weathering rate of the parent material. Using previous work characterizing the physical characteristics of soil across the Hawaii chronosequence to model the contrasting soils, we found that the 0.3 and 20 ka Hawaii soils had similar hydraulic properties; θ values were approximately 0.45 cm3/cm3 and Ks values were 6 cm/hr. However, these Hawaiian soils contrasted and were quantitatively lower than the entire COTM chronosequence. At the 2.1 ka COTM soil, Ks was 17 cm/hr and θ was 0.52-0.65 cm3/cm3 whereas at the 13.9 ka soil, Ks was 12 cm/hr and θ was 0.52 cm3/cm3. The 0.3 ka Hawaiian soil had a 20-30% higher silt content than the 2.1 ka COTM soil. Our models help quantify rates of soil development and hydraulic properties developed through time on volcanic parent materials.

  17. Assessing microbial activities in metal contaminated agricultural volcanic soils--An integrative approach.

    PubMed

    Parelho, C; Rodrigues, A S; Barreto, M C; Ferreira, N G C; Garcia, P

    2016-07-01

    Volcanic soils are unique naturally fertile resources, extensively used for agricultural purposes and with particular physicochemical properties that may result in accumulation of toxic substances, such as trace metals. Trace metal contaminated soils have significant effects on soil microbial activities and hence on soil quality. The aim of this study is to determine the soil microbial responses to metal contamination in volcanic soils under different agricultural land use practices (conventional, traditional and organic), based on a three-tier approach: Tier 1 - assess soil microbial activities, Tier 2 - link the microbial activity to soil trace metal contamination and, Tier 3 - integrate the microbial activity in an effect-based soil index (Integrative Biological Response) to score soil health status in metal contaminated agricultural soils. Our results showed that microbial biomass C levels and soil enzymes activities were decreased in all agricultural soils. Dehydrogenase and β-glucosidase activities, soil basal respiration and microbial biomass C were the most sensitive responses to trace metal soil contamination. The Integrative Biological Response value indicated that soil health was ranked as: organic>traditional>conventional, highlighting the importance of integrative biomarker-based strategies for the development of the trace metal "footprint" in Andosols.

  18. The use of volcanic soil as mineral landfill liner--III. Heavy metals retention capacity.

    PubMed

    Navia, Rodrigo; Fuentes, Bárbara; Diez, María C; Lorber, Karl E

    2005-06-01

    The volcanic soil of Southern Chile was tested for its heavy metal retention capacity. The maximum uptakes for CrO4(2-) (CrVI), Cu(2+), Zn(2+) and Pb(2+) were determined to be 2.74, 5.32, 5.86 and 7.44 mg g(-1), respectively. At a slightly alkaline pH value (7.5), it seems that a precipitation-adsorption process was responsible for the Cu(2+) and Zn(2+) uptake onto volcanic soil. All the determined values are of the same order of magnitude as natural zeolites heavy metals adsorption capacities. In addition, the heavy metals diffusion model through a 1 m volcanic soil mineral liner shows breakthrough times of 21.6, 10.2 and 8.9 years, for Pb(2+), Zn(2+) and Cu(2+), respectively, confirming the trend obtained in the adsorption isotherms. The natural volcanic soil of Southern Chile is an interesting material for possible use as landfill mineral basal sealing. It has an appropriate sealing potential (average Kf value of 5.85 x 10(-9) m s(-1)) and a heavy metals retention capacity comparable with natural zeolites. About two-thirds of the agricultural land in Chile (approximately 0.4 million km2) is derived from volcanic ash, suggesting an important soil volume for future landfill projects, that could be obtained in sufficient quantities from urban building activities.

  19. Cemented Volcanic Soils, Martian Spectra and Implications for the Martian Climate

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Schiffman, P.; Drief, A.; Southard, R. J.

    2004-01-01

    Cemented soils formed via reactions with salts are studied here and provide information about the climate when they formed. Spectroscopic and microprobe studies have been performed on cemented volcanic crusts in order to learn about the composition of these materials, how they formed, and what they can tell us about climatic interactions with surface material on Mars to form cemented soils. These crusts include carbonate, sulfate and opaline components that may all be present in cemented soil units on Mars.

  20. The use of volcanic soil as mineral landfill liner--I. Physicochemical characterization and comparison with zeolites.

    PubMed

    Navia, Rodrigo; Hafner, Georg; Raber, Georg; Lorber, Karl E; Schöffmann, Elke; Vortisch, Walter

    2005-06-01

    The main physicochemical characteristics of the volcanic soil of Southern Chile, with allophane as the main pedogenic mineral phase were analysed and compared with common zeolites (clinoptilolite) of the European market. The ultimate goal of this study was to test volcanic soil for the use as mineral landfill liner. The main results indicated that the clay and silt fractions together of the volcanic soil were between 38 and 54%. The buffering capacity of the volcanic soil was higher compared with the studied zeolites, whereas the cationic exchange capacity of the volcanic soil (between 5.2 and 6.5 cmol + kg(-1)) is of the same order of magnitude of the studied zeolites (between 9.7 and 11.4 cmol + kg(-1)). Moreover, the anionic exchange capacity of the volcanic soil was higher compared to the zeolites analysed. The hydraulic conductivity of the volcanic soil, measured in the laboratory at maximum proctor density, ranges between 5.16 x 10(-9) and 6.48 x 10(-9) m s(-1), a range that is comparable to the value of 4.51 x 10(-9) m s(-1) of the studied zeolite. The Proctor densities of the volcanic soil are in a lower range (between 1.11 and 1.15 g ml(-1)) compared with zeolites (between 1.19 and 1.34 g ml(-1)). The volcanic soil physicochemical characteristics are comparable to all the requirements established in the Austrian landfill directive (DVO, 2000). Therefore, the use as mineral landfill basal sealing of the analysed volcanic soil appears reasonable, having a pollutant adsorption capacity comparable to zeolites. It is of special interest for Southern Chile, because there are no alternative mineral raw materials for basal liners of landfills.

  1. Soil radon measurements as a potential tracer of tectonic and volcanic activity.

    PubMed

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-04-15

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009-2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

  2. Soil radon measurements as a potential tracer of tectonic and volcanic activity

    PubMed Central

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-01-01

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009–2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes. PMID:27079264

  3. Soil radon measurements as a potential tracer of tectonic and volcanic activity

    NASA Astrophysics Data System (ADS)

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-04-01

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009–2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

  4. Volcanic emissions from soils at the base of La Fossa volcano, Vulcano island, Italy

    NASA Astrophysics Data System (ADS)

    Obenholzner, J. H.; Parks, J. L.

    2006-12-01

    A top-sealed plastic tube with a diameter of ca. 15 cm had been buried vertically at the base of La Fossa volcano, Volcano island, Italy, next to the front of the obsidian flow. The tube had been filled with quartz wool to condense vapors emanating from the soil. At ca. 75 cm below the surface the sample had been exposed to vapors from Sept. 2005 to April 2006. The leached sample had not been in touch with the ground. Another glass wool cushion (ca. 3 cm thick) had been underneath to minimize capillary effects. Leaching of the quartz wool and ICP-MS analysis documented positive values for: Mg, Al, Si, P, K, Ca, Cr, Mn, Ni, Cu, Zn, Cd, Sn, Pb. Leaching with nitric acid documented also V and Fe. Acid leaching produced higher values for all elements, except K and Sn, than leaching with deionized water. Negative values had been obtained for As, Se, Mo. Influence from soil breathing can be excluded as the active fumaroles contain As and Se. This experiment documents for the first time an unknown element transport by vapors/gases through a volcanic edifice interacting with hydrothermal and magmatic gases. It remains unknown if elements detected are entering the atmosphere or are getting adsorbed onto the volcanic ash soil particles derived from reworked surge beds. This question is very important as soils might be an unknown filter medium to filter volcanically polluted air in case of major volcanic crises. Data can be obtained from the authors.

  5. Irreversibility of 2,4-Dichlorophenoxyacetic Acid Sorption onto a Volcanic Ash Soil

    NASA Astrophysics Data System (ADS)

    Mon, E.; Kawamoto, K.; Komatsu, T.; Moldrup, P.

    2008-12-01

    Pesticide sorption and desorption in soils are key processes governing fate and transport of pesticides in the soil environment. The irreversibility (or hysteresis) in the processes of pesticide sorption and desorption needs to be known to accurately predict behavior of pesticides in soil systems. 2,4-dichlorophenoxyacetic acid (2,4-D) is a widely used pesticide in agriculture fields. However, only few studies of 2,4-D adsorption onto Andosols (volcanic ash soils) have been published, and the knowledge of 2,4-D desorption onto Andosols is very limited. In this study, a volcanic ash soil sampled from a pasture site in Nishi-Tokyo, Japan was used as a sorbent in order to investigate the irreversibility of 2,4-D sorption. For comparison, a pure clay mineral (kaolinite) obtained from Clay Science Society of Japan (CSSJ) was also used. 2,4-D solutions with three concentrations (0.011, 0.022 and 0.045 mmol/L) were prepared in artificial rain water (ARW= 0.085mM NaCl + 0.015mM CaCl2) to simulate field conditions. To prepare the sample solutions, the solid mass/liquid volume ratio of 1:10 was used for both sorbents (volcanic ash soil and kaolinite). The experiments were conducted in triplicate using a batch method under different pH conditions to examine the effect of pH. Desorption was measured during a equilibration procedure: After removal of 7 mL of supernatant in the sorption step, 7 mL of ARW excluding 2,4-D was added to the sample solution after which, it was equilibrated and centrifuged. The procedure was performed sequentially three or four times to obtain a desorption isotherm. Sorption and desorption generally followed Freundlich isotherms. The results showed markedly effects of pH on 2,4-D sorption and desorption in both the soil and kaolinite, with the percentage of sorption increasing with decreasing pH whereas the percentage of desorption decreased. There was a larger adsorption-desorption hysteresis in the volcanic ash soil as compared to kaolinite

  6. The structural-functional organization of thermotolerant complexes of actinomycetes in desert and volcanic soils

    NASA Astrophysics Data System (ADS)

    Zenova, G. M.; Kurapova, A. I.; Lysenko, A. M.; Zvyagintsev, D. G.

    2009-05-01

    It has been found that the number of thermotolerant actinomycetes in strongly heated soils of deserts and volcanic regions is comparable to or exceeds the number of mesophilic actinomycetes. Among the latter group, streptomyces usually predominate; among thermotolerant actinomycetes, representatives of the Micromonospora, Streptosporangium, Actinomadura, Saccharopolyspora, Microtetraspora, and Microbispora genera are identified. Thermotolerant actinomycetes display the full cycle of their development in these soils. The method of fluorescent in situ hybridization has made it possible to determine that mycelial forms predominate among the metabolically active representatives of Actinobacteria; their portion increases with the rise in the temperature of soil incubation.

  7. Risk of classic Kaposi sarcoma with residential exposure to volcanic and related soils in Sicily

    PubMed Central

    Pelser, Colleen; Dazzi, Carmelo; Graubard, Barry I.; Lauria, Carmela; Vitale, Francesco; Goedert, James J.

    2009-01-01

    Purpose Before AIDS, endemic (African) Kaposi sarcoma (KS) was noted to occur in volcanic areas and was postulated to result from dirt chronically embedded in the skin of the lower extremities. The primary cause of all KS types is KS-associated herpesvirus (KSHV) infection, but co-factors contribute to the neoplasia. We investigated whether residential exposure volcanic or related soils was associated with the risk of classic Kaposi sarcoma (cKS) in Sicily. Methods Risk of incident cKS (n=141) compared to population-based KSHV seropositive controls (n=123) was estimated for residential exposure to four types of soil, categorized with maps from the European Soil Database and direct surveying. Questionnaire data provided covariates. Results Residents in communities high in luvisols were approximately 2.7-times more likely to have cKS than those in communities with no luvisols. Risk was not specific for cKS on the limbs, but it was elevated approximately 4–5-fold with frequent bathing or tap water drinking in high luvisols communities. Risk was unrelated to communities high in andosols, tephra, or clay soils. Conclusions Iron and alumino-silicate clay, major components of luvisols, may increase cKS risk, but formal investigation and consideration of other soil types and exposures are needed. PMID:19576540

  8. Methanotrophic activity and bacterial diversity in volcanic-geothermal soils at Pantelleria island (Italy)

    NASA Astrophysics Data System (ADS)

    Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.

    2014-04-01

    Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic/geothermal soils are source of methane, but also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria island (Italy), Favara Grande, whose total methane emission was previously estimated in about 2.5 t a-1. Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values up to 950 ng g-1 dry soil h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile and the maximum methane consumption was measured in the top-soil layer but values > 100 ng g-1 h-1 were maintained up to a depth of 15 cm. The highest consumption rate was measured at 37 °C, but a still recognizable consumption at 80 °C (> 20 ng g-1 h-1) was recorded. In order to estimate the bacterial diversity, total soil DNA was extracted from Favara Grande and analysed using a Temporal Temperature Gradient gel Electrophoresis (TTGE) analysis of the amplified bacterial 16S rRNA gene. The three soil samples were probed by PCR using standard proteobacterial primers and newly designed verrucomicrobial primers targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected in sites FAV2 and FAV3, but not in FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site FAV2 pointed out a high diversity of gammaproteobacterial methanotrophs distantly related to Methylococcus/Methylothermus genera and the presence of the newly discovered acido-thermophilic methanotrophs

  9. Magnesium retention on the soil exchange complex controlling Mg isotope variations in soils, soil solutions and vegetation in volcanic soils, Iceland

    NASA Astrophysics Data System (ADS)

    Opfergelt, S.; Burton, K. W.; Georg, R. B.; West, A. J.; Guicharnaud, R. A.; Sigfusson, B.; Siebert, C.; Gislason, S. R.; Halliday, A. N.

    2014-01-01

    Understanding the biogeochemical cycle of magnesium (Mg) is not only crucial for terrestrial ecology, as this element is a key nutrient for plants, but also for quantifying chemical weathering fluxes of Mg and associated atmospheric CO2 consumption, requiring distinction of biotic from abiotic contributions to Mg fluxes exported to the hydrosphere. Here, Mg isotope compositions are reported for parent basalt, bulk soils, clay fractions, exchangeable Mg, seasonal soil solutions, and vegetation for five types of volcanic soils in Iceland in order to improve the understanding of sources and processes controlling Mg supply to vegetation and export to the hydrosphere. Bulk soils (δ26Mg = -0.40 ± 0.11‰) are isotopically similar to the parent basalt (δ26Mg = -0.31‰), whereas clay fractions (δ26Mg = -0.62 ± 0.12‰), exchangeable Mg (δ26Mg = -0.75 ± 0.14‰), and soil solutions (δ26Mg = -0.89 ± 0.16‰) are all isotopically lighter than the basalt. These compositions can be explained by a combination of mixing and isotope fractionation processes on the soil exchange complex. Successive adsorption-desorption of heavy Mg isotopes leads to the preferential loss of heavy Mg from the soil profile, leaving soils with light Mg isotope compositions relative to the parent basalt. Additionally, external contributions from sea spray and organic matter decomposition result in a mixture of Mg sources on the soil exchange complex. Vegetation preferentially takes up heavy Mg from the soil exchange complex (Δ26Mgplant-exch = +0.50 ± 0.09‰), and changes in δ26Mg in vegetation reflect changes in bioavailable Mg sources in soils. This study highlights the major role of Mg retention on the soil exchange complex amongst the factors controlling Mg isotope variations in soils and soil solutions, and demonstrates that Mg isotopes provide a valuable tool for monitoring biotic and abiotic contributions of Mg that is bioavailable for plants and is exported to the hydrosphere.

  10. Linking trace metals and agricultural land use in volcanic soils--a multivariate approach.

    PubMed

    Parelho, C; Rodrigues, A S; Cruz, J V; Garcia, P

    2014-10-15

    The concern about the environmental impacts caused by agriculture intensification is growing as large amounts of nutrients and contaminants are introduced into soil ecosystems. Volcanic soils are unique naturally fertile resources extensively used for agricultural purposes, with particular physical and chemical properties that may result in possible accumulation of toxic substances, such as metals. Within this particular geological context, the present study aims to evaluate the impact of different agricultural systems (conventional, traditional and organic) in trace metal (TM) soil pollution and define the tracers for each one. Physicochemical properties and TM contents in agricultural topsoils were determined. Enrichment Factors (EF) were calculated to distinguish geogenic and anthropogenic contribution to TM contents in agricultural soils. An ensemble of multivariate statistical analyses (PCA and FDA) was performed to reduce the multidimensional space of variables and samples, thus defining a set of TM as tracers of distinct agricultural farming systems. Results show that agricultural soils have low organic matter content (<5%) compared to reference soil (>30%); in addition, electric conductivity in conventional farming soils is higher (262.3 ± 162.6 μS cm(-1)) while pH is lower (5.8 ± 0.3). Regarding metal inputs, V, Ba and Hg soil contents are mainly of geogenic origin, while Li, P, K, Cr, Mn, Ni, Cu, Zn, As, Mo, Cd and Pb result primarily from anthropogenic inputs. Li revealed to be a tracer of agricultural pollution in conventional farming soils, whereas V allowed the discrimination of traditional farming soils. This study points to agriculture as a diffuse source of anthropogenic TM soil pollution and is the first step to identify priority chemicals affecting agricultural Andosols.

  11. Organic matter protection as affected by the mineral soil matrix: allophanic vs. non-allophanic volcanic ash soils

    NASA Astrophysics Data System (ADS)

    Nierop, K. G. J.; Kaal, J.; Jansen, B.; Naafs, D. F. W.

    2009-04-01

    Volcanic ash soils (Andosols) contain the largest amounts of organic carbon of all mineral soil types. Chemical (complexes of organic matter with allophane, Al/Fe) and physical (aggregation) mechanisms are protecting the carbon from decomposition. While allophanic Andosols are dominated by short range order minerals such as allophane, imogolite and ferrihydrite, organic matter-Al/Fe complexes dominate non-allophanic Andosols. Consequently, chemical interactions between the mineral soil matrix and organic matter differ between these two soil types. This difference could potentially lead to different organic matter compositions. In this study, the organic matter of Ah horizons of an allophanic Andosol with a non-allophanic Andosol from Madeira Island is compared using analytical pyrolysis. Both volcanic soil types showed a relative decrease of lignin-derived pyrolysis products with depth, but this decrease was more pronounced in the allophanic Andosol. Polysaccharides were more abundant in the allophanic Ah horizon, particularly at lower depth, and this was also the case for the non-plant-derived N-containing polysaccharide chitin. Most likely, these biopolymers are adsorbed onto short range order minerals such as allophane and therefore were better protected in the allophanic Andosol. In addition, the higher chitin contents combined with the more pronounced lignin degradation suggests a higher fungal activity. Aliphatic pyrolysis products (n-alkenes/n-alkanes, fatty acids) were relatively more enriched in the non-allophanic Andosol. Lower microbial activity caused by the more acidic pH and higher levels of (toxic) aluminium are the most plausible reasons for the accumulation of these compounds in the non-allophanic Andosol. Although the allophanic and non-allophanic Andosol resembled each other in containing biopolymer groups of the same orders of magnitudes, in particular the contents of chitin and aliphatic compounds were distinctly affected by the differences in

  12. Iron Oxides from Volcanic Soils as Potential Catalysts in the Water Gas Shift Reaction

    SciTech Connect

    Pizarro, C.; Escudey, M.; Moya, S.A.; Fabris, J.D.

    2005-04-26

    This study was focused on changes of the iron oxide mineralogy with temperature of two Chilean soils (Andisol and Ultisol) derived from volcanic materials and their use as iron-based catalysts in the water gas shift reaction (WGSR). Ultisol materials produced about twice as much hydrogen than did those from Andisol upon WGSR, but in both cases hydrogen yielding increased as the heating temperature of the soil materials increased from 124 deg. C to 500 deg. C. The room temperature Moessbauer spectra showed an increase of the relative proportion of the magnetically ordered components as temperature increased. Higher heating temperature produced a negative effect on the catalytic activity, whereas the organic matter destruction led to a positive effect, due to an increasing exposition of the iron oxide surfaces; heating the soil sample at 600 deg. C induced changes on the iron oxide mineralogy with a significant decrease of the catalytic activity.

  13. Methanotrophic activity and diversity of methanotrophs in volcanic geothermal soils at Pantelleria (Italy)

    NASA Astrophysics Data System (ADS)

    Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.

    2014-10-01

    Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic or geothermal soils are not only a source of methane, but are also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria (Italy), Favara Grande, whose total methane emission was previously estimated at about 2.5 Mg a-1 (t a-1). Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values of up to 59.2 nmol g-1 soil d.w. h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile, the maximum methane consumption was measured in the top-soil layer, and values greater than 6.23 nmol g-1 h-1 were still detected up to a depth of 13 cm. The highest consumption rate was measured at 37 °C, but a still detectable consumption at 80 °C (> 1.25 nmol g-1 h-1) was recorded. The soil total DNA extracted from the three samples was probed by Polymerase Chain Reaction (PCR) using standard proteobacterial primers and newly designed verrucomicrobial primers, targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected at sites FAV2 and FAV3, but not at FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site (FAV2) pointed to a high diversity of gammaproteobacterial methanotrophs, distantly related to Methylocaldum-Metylococcus genera, and the presence of the newly discovered acido-thermophilic Verrucomicrobia methanotrophs. Alphaproteobacteria of the genus Methylocystis were isolated from enrichment cultures under a methane

  14. Influence of management practices on C stabilization pathways in agricultural volcanic ash soils (Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Hernandez, Zulimar; María Álvarez, Ana; Carral, Pilar; de Figueiredo, Tomas; Almendros, Gonzalo

    2014-05-01

    Although C stabilization mechanisms in agricultural soils are still controversial [1], a series of overlapped pathways has been suggested [2] such as: i) insolubilization of low molecular weight precursors of soil organic matter (SOM) with reactive minerals through physical and chemical bonding, ii) selective accumulation of biosynthetic substances which are recalcitrant because of its inherent chemical composition, and iii) preservation and furter diagenetic transformation of particulate SOM entrapped within resistant microaggregates, where diffusion of soil enzymes is largely hampered. In some environments where carbohydrate and N compounds are not readily biodegraded, e.g., with water saturated micropores, an ill-known C stabilization pathway may involve the formation of Maillard's reaction products [3]. In all cases, these pathways converge in the formation of recalcitrant macromolecular substances, sharing several properties with the humic acid (HA) fraction [4]. In template forests, the selective preservation and further microbial reworking of plant biomass has been identified as a prevailing mechanism in the accumulation of recalcitrant SOM forms [5]. However, in volcanic ash soils with intense organomineral interactions, condensation reactions of low molecular weight precursors with short-range minerals may be the main mechanism [6]. In order to shed some light about the effect of agricultural management on soil C stabilization processes on volcanic ash soils, the chemical composition of HA and some structural proxies of SOM informing on its origin and potential resistance to biodegradation, were examined in 30 soils from Canary Islands (Spain) by visible, infrared (IR) and 13C nuclear magnetic resonance (NMR) spectroscopies, elementary analysis and pyrolytic techniques. The results of multivariate treatments, suggested at least three simultaneous C stabilization biogeochemical trends: i) diagenetic alteration of plant biomacromolecules in soils receiving

  15. Ten years of soil CO2 continuous monitoring on Mt. Etna: Exploring the relationship between processes of soil degassing and volcanic activity

    NASA Astrophysics Data System (ADS)

    Liuzzo, Marco; Gurrieri, Sergio; Giudice, Gaetano; Giuffrida, Giovanni

    2013-08-01

    The measurement of soil CO2 flux variations is a well-established practice in many volcanic areas around the world. Until recently, however, most of these were made using direct sampling methods. These days, a variety of automatic devices providing real-time data now make the continuous monitoring of volcanic areas possible. A network of automatic geochemical monitoring stations (EtnaGas network) was developed by INGV Palermo and installed at various sites on the flanks of Mt. Etna. Here, we present a large set of soil CO2 flux data recorded by the network, dating back 10 years, a period in which several noteworthy eruptive phenomena occurred. Our statistical analysis strongly suggests that anomalous measurements of soil CO2 flux are attributable to volcanic origin and in almost all cases precede volcanic activity. Here, we present the actual data series recorded by EtnaGAS and an interpretative model of the expected behavior of soil CO2 flux (in terms of increase-decrease cycles), which corresponded well with the volcanic activity during this period. Through the use of a comparative approach, incorporating both volcanological and geochemical data, the global soil CO2 flux trends are put into a coherent framework, highlighting close links between the time flux variations and volcanic activities. These insights, made possible from 10 years of uninterrupted data, confirm the importance of continuous monitoring of volcanic soil degassing, and may contribute in the forecasting of imminent eruptive activity or the temporal evolution of an in-progress eruption, therefore facilitating Civil Defense planning in volcanic areas under high-hazard conditions.

  16. Speciation of vanadium in urban, industrial and volcanic soils by a modified Tessier method.

    PubMed

    Orecchio, Santino; Amorello, Diana; Barreca, Salvatore; Pettignano, Alberto

    2016-03-01

    Vanadium (V) concentrations in industrial, urban and volcanic soils were sequentially extracted using a modified Tessier's method. The voltammetric technique was used to determine V concentrations in solutions obtained from the various extraction steps. At the reference stations, the V concentrations (sum of four individual fractions) in soils ranged from 0.72 to 0.24 g kg(-1) dry weight (d.w.) with a mean value of 0.18 g kg(-1) d.w. V concentrations in soils of the Palermo urban area ranged from 0.34 to 2.1 g kg(-1) d.w., in the Milazzo (industrial) area between 0.26 and 5.4 g kg(-1) d.w. and in the volcanic area near Mt. Etna from 0.91 to 2.9 g kg(-1) d.w. When the V concentrations around Mt. Etna were compared with those obtained at the reference stations, it was confirmed that Mt. Etna is a continuous source of V. In all the samples analyzed, the majority of V (from 94 to 100%) was detected in the fourth fraction.

  17. Ammonia emissions from urea application to permanent pasture on a volcanic soil

    NASA Astrophysics Data System (ADS)

    Salazar, F.; Martínez-Lagos, J.; Alfaro, M.; Misselbrook, T.

    2012-12-01

    Agriculture is the largest source of ammonia (NH3) emission to the atmosphere, deriving mainly from livestock urine and manures, but fertilizer applications to pastures and crops also represent an important source. In Chile, where agriculture and cattle production are important activities (accounting for 4.5% of GDP along with the forestry sector), there are very few published data regarding NH3 emissions from pasture and crop fertilization. This study aimed to provide the first empirical field data for Chile on N losses due to NH3 volatilization following urea application to permanent pasture on a volcanic soil and to assess the influence of environmental conditions on emissions. Four field experiments were carried out on a volcanic acid soil using the micrometeorological integrated horizontal flux (IHF) mass balance method. Measurements were made in winter 2005 and 2007, and spring 2007 and 2008 following urea N fertilization to a permanent pasture at a rate equivalent to 100 kg N ha-1. Cumulative NH3 emissions over the measurement period were 1.4 and 7.7 kg N ha-1 for winter applications, and 12.2 and 26.7 kg N ha-1 for spring dressings. These N losses due to NH3 volatilization are within the range of emissions reported elsewhere. Consideration of urea application timing in Chile, with regards to weather and soil conditions, could have important consequences on minimising potential N losses via volatilization with associated financial benefits to farmers.

  18. Impact of river overflowing on trace element contamination of volcanic soils in south Italy: part I. Trace element speciation in relation to soil properties.

    PubMed

    Adamo, P; Zampella, M; Gianfreda, L; Renella, G; Rutigliano, F A; Terribile, F

    2006-11-01

    Volcanic soils affected by different numbers of polluted river flooding events were investigated. Chromium and Cu were the major soil contaminants. Nickel, Fe, Zn and Mn total content never exceeded the Italian mandatory limits. The distribution of Cr and Cu total contents among studied soils indicated that only Cr contamination was related to overflowing events. In polluted soils, sequential chemical extractions revealed a preferential association of Cr and Cu with organic forms. A progressive Cr insolubilization with ageing was observed. Significant amounts of Cr and Cu were extracted by NH(4)-oxalate, suggesting metals association with short-range-order aluminosilicates and organo-mineral complexes. Possible methodological drawbacks in the use of the EU-BCR chemical speciation protocol on volcanic soils are discussed. Micromorphology and SEM/WDS analyses revealed Cr and Cu enriched silt and clay coatings in surface and subsurface soil horizons, suggesting a transfer of metal-rich sediments along the soil pore network with water movement.

  19. Soil radon measurements as potential tracer of seismic and volcanic activity at Etna

    NASA Astrophysics Data System (ADS)

    Neri, Marco; Giammanco, Salvatore; Galli, Gianfranco; Ferrera, Elisabetta

    2014-05-01

    Radon is a radioactive noble gas present in all rocks of the Earth. It's used by the scientific community as a tracer of natural phenomena related to outgassing from the soil along faults, fractures and crustal discontinuity. Recently, radon has also been used on active volcanoes such as Etna, both as a precursor of volcanic phenomena as well as in the study of the dynamics of faults. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) performs discrete and continuous measurements of radon from soil at Etna since 2002. First studies concerned measurements of radon and thoron emissions from soil carried out on the E and SW flanks of Etna, in zones characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds, producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. These studies confirmed that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover. INGV permanent radon monitoring network was installed in July 2005. First results were obtained during the July 2006 eruption. The radon signal recorded at Torre del Filosofo (TdF, ~2950 m asl) was compared with volcanic tremor and thermal radiance data. The onset of explosive activity and a lava fountaining episode were preceded by some hours with increases in radon activity and more gradual increases in volcanic tremor. After 2006, Etna produced dozens of paroxysmal episodes from a new vent opened on the eastern flank of the Southeast Crater (summit area), that have built up a new, huge pyroclastic cone. In many cases we observed increase in radon activity some hours before the eruptive events. These observations suggest that radon emissions from the TdF zone are sensitive to the local geodynamic pressure induced by magma dynamics in the conduit systems. Other promising results were

  20. Pyrolysis-AMS Study of Age Structure of SOC in Volcanic Soils on Kohala Volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Grant, K. E.; Galy, V.; Derry, L. A.

    2014-12-01

    Soil organic carbon (SOC) is a complex substrate; the soil matrix has a wide array of chemical inputs, leading to a heterogeneous mixture of carbon compounds. In volcanic soils on Kohala Mountain, Hawaii Island, old organic carbon (OC) (>10,000 years) is associated with short-range order (SRO) minerals with large, reactive surface areas (Torn et al., 1997). Large variations in precipitation generate significant changes in soil pH, secondary minerals and soil redox state. A study to measure the age distribution in a given sample of SOC by the ramped pyrolysis-AMS technique was carried out at Woods Hole NOSAMS facility. Five soil samples, from three sites (precipitation = 2.4m/year, 2.3m/year, 1.78m/year, respectively) on a 350 ka volcanic (Pololu) substrate were analyzed. Samples were freeze-dried, homogenized, and combusted under a programed temperature pyrolysis regime from 25 to 900°C; evolved CO2 was collected in fractions for 14C analysis. The abundance of SRO minerals is characterized through sequential extractions and total elemental analysis. Results include: 1.) The Pu'u Eke profile (2.4m/year), older carbon (bulk radiocarbon age: 2530 years) is deeper (63-74cm) in the soil profile, but it is thermally less stable (thermograph Tmax: 314°C) than the younger carbon, which was in the associated with the 25-36cm sample (radiocarbon age: 1030yr) and Tmax: 324°C. The top horizon of the profile (13-21cm) had a modern radiocarbon age, but a Tmax: 396°C. 2.) The high precipitation site has significantly younger OC (2698 yr) than the drier site (7585 yr). This is coincident with changing redox conditions and loss of nano-crystalline iron oxide minerals (ferrihydrite) from the wet site. 3.) In a given sample, the age distribution is fairly uniform. The initial results support the hypothesis that nano-crystalline ferrihydrite acts to stabilize OC, as older carbon is found in the dryer, ferrihydrite rich sites, while at the wet, Fe-poor site 14C ages were

  1. The Natural Terrestrial Carbon Sequestration Potential of Rocky Mountain Soils Derived From Volcanic Bedrock

    NASA Astrophysics Data System (ADS)

    Yager, D. B.; Burchell, A.; Johnson, R. H.

    2008-12-01

    The possible economic and environmental ramifications of climate change have stimulated a range of atmospheric carbon mitigation actions, as well as, studies to understand and quantify potential carbon sinks. However, current carbon management strategies for reducing atmospheric emissions underestimate a critical component. Soils represent between 18 - 30% of the terrestrial carbon sink needed to prevent atmospheric doubling of CO2 by 2050 and a crucial element in mitigating climate change, natural terrestrial sequestration (NTS), is required. NTS includes all naturally occurring, cumulative, biologic and geologic processes that either remove CO2 from the atmosphere or prevent net CO2 emissions through photosynthesis and microbial fixation, soil formation, weathering and adsorption or chemical reactions involving principally alumino- ferromagnesium minerals, volcanic glass and clays. Additionally, NTS supports ecosystem services by improving soil productivity, moisture retention, water purification and reducing erosion. Thus, 'global climate triage' must include the protection of high NTS areas, purposeful enhancement of NTS processes and reclamation of disturbed and mined lands. To better understand NTS, we analyzed soil-cores from Colorado, Rocky Mountain Cordillera sites. North-facing, high-plains to alpine sites in non-wetland environments were selected to represent temperate soils that may be less susceptible to carbon pool declines due to global warming than soils in warmer regions. Undisturbed soils sampled have 2 to 6 times greater total organic soil carbon (TOSC) than global TOSC averages (4 - 5 Wt. %). Forest soils derived from weathering of intermediate to mafic volcanic bedrock have the highest C (34.15 Wt. %), C:N (43) and arylsulfatase (ave. 278, high 461 μg p-nitrophenol/g/h). Intermediate TOSC was identified in soils derived from Cretaceous shale (7.2 Wt. %) and Precambrian, felsic gneiss (6.2 Wt. %). Unreclaimed mine-sites have the lowest C (0

  2. Ground Penetrating Radar (GPR) Signatures of Lacustrine Soils in Volcanic Basins of Mexico

    NASA Astrophysics Data System (ADS)

    Carreon-Freyre, D.; Oleschko, K.; Cerca, M.

    2002-12-01

    Ground Penetrating Radar (GPR) profiles have been collected in volcanic and lacustrine basins of Mexico in order to obtain radar signatures and correlate electromagnetic wave propagation with their near-surface stratigraphy. Study sites included Pleistocene to Recent lacustrine sequences in Chalco and Texcoco, near Mexico City, and a Pliocene to Quaternary fluvio-lacustrine sequence in the Queretaro Valley, 250 Km to the northwest. All the sequences present alterning layers of soils, fluvio-lacustrine sediments, pyroclastic and volcanic rocks. GPR method is used because of the sensitivity of the propagation of electromagnetic waves to the granulometric variations and water content of sediments (water molecules polarization). Profiles were carried out with a Zond 12c GPR (Radar Systems Inc.), using four main prospecting frequencies: 2000, 900, 300 and 100 MHz. The purpose of using these frequencies is to evaluate different ranges of depths of investigation and resolution for each site and to relate attenuation and variations in amplitude with impedances and reflection coefficients for stratigraphic associations such as clay-sand, silt-clay and pyroclastics-silt. The analysis of multiple sets of profiles in the studied areas and their correlation with the observed near-surface stratigraphy permits the identification of radar signatures for each depositional condition. GPR characterization also allowed to associate radar signatures with the evolution of fracturing within the sequence. In particular, the Chalco and Queretaro sites are affected by fracturing, an increasing problem in several urbanized areas of Mexico and the world. This phenomenon is generally associated to ground-water withdrawal but its geometry is related closely to the regional structural pattern. Another factor that influences the propagation and morphology of near-surface fracturing in volcanic valleys is their highly heterogeneous stratigraphy. Therefore, the propagation of electromagnetic waves

  3. In vitro methane removal by volcanic pumice soil biofilter columns over one year.

    PubMed

    Pratt, Chris; Walcroft, Adrian S; Tate, Kevin R; Ross, Des J; Roy, Réal; Reid, Melissa Hills; Veiga, Patricia W

    2012-01-01

    Soil methane (CH(4)) biofilters, containing CH(4)-oxidizing bacteria (methanotrophs), are a promising technology for mitigating greenhouse gas emissions. However, little is known about long-term biofilter performance. In this study, volcanic pumice topsoils (0-10 cm) and subsoils (10-50 cm) were tested for their ability to oxidize a range of CH(4) fluxes over 1 yr. The soils were sampled from an 8-yr-old and a 2-yr-old grassed landfill cover and from a nearby undisturbed pasture away from the influence of CH(4) generated by the decomposing refuse. Methane was passed through the soils in laboratory chambers with fluxes ranging from 0.5 g to 24 g CH(4) m(-3) h(-1). All topsoils efficiently oxidized CH(4). The undisturbed pasture topsoil exhibited the highest removal efficiency (24 g CH(4) m(-3) h(-1)), indicating rapid activation of the methanotroph population to the high CH(4) fluxes. The subsoils were less efficient at oxidizing CH(4) than the topsoils, achieving a maximum rate oxidation rate of 7 g CH(4) m(-3) h(-1). The topsoils exhibited higher porosities; moisture contents; surface areas; and total C, N, and available-P concentrations than the subsoils, suggesting that these characteristics strongly influence growth and activity of the CH(4)-oxidizing bacteria. Soil pH values and available-P levels gradually declined during the trial, indicating a need to monitor chemical parameters closely so that adjustments can be made when necessary. However, other key soil physicochemical parameters (moisture, total C, total N) increased over the course of the trial. This study showed that the selected topsoils were capable of continually sustaining high CH(4) removal rates over 1 yr, which is encouraging for the development of biofilters as a low-maintenance greenhouse gas mitigation technology.

  4. Flood basalt volcanism, end-Triassic deforestation, and intense weathering of soils and bedrock

    NASA Astrophysics Data System (ADS)

    van de Schootbrugge, Bas; Lindström, Sofie; Pross, Jörg; Dybkjaer, Karen; Heunisch, Carmen; Petschick, Rainer; Lyachenko, Lara; Püttmann, Willhelm; Oschmann, Wolfgang

    2010-05-01

    The end-Triassic mass-extinction on land was characterized by the widespread dieback of gymnospermous forests across the northern hemisphere and their transient replacement by ferns and fern allies. These floral changes are thought to have been triggered by the eruption of 2 million kubic kilometers of basalt belonging to the Central Atlantic Magmatic Province, releasing noxious and greenhouse gases into the atmosphere. Here, we provide evidence for the dramatic consequences of deforestation during the latest Triassic in the form of intense erosion of soils and the weathering of bedrock across northwest Europe. Together with abundant fern spores, representing a pioneer vegetation, we find enhanced levels of kaolinite in the boundary beds, indicating chemical weathering. In palynological samples from cores that span the Triassic-Jurassic boundary in Sweden, Denmark and Germany we notice abundant reworked Carboniferous spores, reworked Silurian and Devonian acritarchs, and mycorrhizal fungal remains. The latter suggest soils were being eroded across the Germanic Basin. In Northern Germany, Denmark, and Sweden, Paleozoic palynomorphs were reworked from the Fennoscandian Shield, while in Southern Germany such palynomorphs may have originated from the Bohemian Massive. The contemporaneous, intense weathering of bed rocks and soil erosion on landmasses during the latest Triassic was likely a direct result of deforestation, but was probably exacerbated by acid rain and greenhouse warming due to the emission of sulfur and carbon dioxide from volcanic activity.

  5. Impacts of Dust on Tropical Volcanic Soil Formation: Insights from Strontium and Uranium-Series Isotopes in Soils from Basse-Terre Island, French Guadeloupe

    NASA Astrophysics Data System (ADS)

    Pereyra, Y.; Ma, L.; Sak, P. B.; Gaillardet, J.; Buss, H. L.; Brantley, S. L.

    2015-12-01

    Dust inputs play an important role in soil formation, especially for thick soils developed on tropical volcanic islands. In these regions, soils are highly depleted due to intensive chemical weathering, and mineral nutrients from dusts have been known to be important in sustaining soil fertility and productivity. Tropical volcanic soils are an ideal system to study the impacts of dust inputs on the ecosystem. Sr and U-series isotopes are excellent tracers to identify sources of materials in an open system if the end-members have distinctive isotope signatures. These two isotope systems are particularly useful to trace the origin of atmospheric inputs into soils and to determine rates and timescales of soil formation. This study analyzes major elemental concentrations, Sr and U-series isotope ratios in highly depleted soils in the tropical volcanic island of Basse-Terre in French Guadeloupe to determine atmospheric input sources and identify key soil formation processes. We focus on three soil profiles (8 to 12 m thick) from the Bras-David, Moustique Petit-Bourg, and Deshaies watersheds; and on the adjacent rivers to these sites. Results have shown a significant depletion of U, Sr, and major elements in the deep profile (12 to 4 m) attributed to rapid chemical weathering. The top soil profiles (4 m to the surface) all show addition of elements such as Ca, Mg, U, and Sr due to atmospheric dust. More importantly, the topsoil profiles have distinct Sr and U-series isotope compositions from the deep soils. Sr and U-series isotope ratios of the top soils and sequential extraction fractions confirm that the sources of the dust are from the Saharan dessert, through long distance transport from Africa to the Caribbean region across the Atlantic Ocean. During the transport, some dust isotope signatures may also have been modified by local volcanic ashes and marine aerosols. Our study highlights that dusts and marine aerosols play important roles in element cycles and

  6. Ammonia oxidizers are pioneer microorganisms in the colonization of new acidic volcanic soils from South of Chile.

    PubMed

    Hernández, Marcela; Dumont, Marc G; Calabi, Marcela; Basualto, Daniel; Conrad, Ralf

    2014-02-01

    Ammonia oxidation, performed by specialized microorganisms belonging to the Bacteria and Archaea, is the first and most limiting step of soil nitrification. Nitrification has not yet been examined in young volcanic soils. The aim of the present work was to evaluate the abundance and diversity of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in acidic volcanic soils (andisols) of different defined ages to determine their relative contribution to nitrification and soil colonization. Soil was collected from three vegetated sites on Llaima Volcano (Chile) recolonized after lava eruptions in 1640, 1751 and 1957. Quantitative polymerase chain reaction, terminal restriction fragment length polymorphism and clone sequence analyses of the amoA gene were performed for the AOA and AOB communities. All soils showed high nitrification potentials, but they were highest in the younger soils. Archaeal amoA genes outnumbered bacterial amoA genes at all sites, and AOA abundances were found to be proportional to the nitrification potentials. Sequencing indicated the presence of AOA related to Nitrososphaera and Nitrosotalea, and AOB related primarily to Nitrosospira and sporadically to Nitrosomonas. The study showed that both AOA and AOB are early colonizers of andisols, but that AOA outnumber AOB and play an important role in nitrification.

  7. Microbial life in volcanic/geothermal areas: how soil geochemistry shapes microbial communities

    NASA Astrophysics Data System (ADS)

    Gagliano, Antonina Lisa; D'Alessandro, Walter; Franzetti, Andrea; Parello, Francesco; Tagliavia, Marcello; Quatrini, Paola

    2015-04-01

    Extreme environments, such as volcanic/geothermal areas, are sites of complex interactions between geosphere and biosphere. Although biotic and abiotic components are strictly related, they were separately studied for long time. Nowadays, innovative and interdisciplinary approaches are available to explore microbial life thriving in these environments. Pantelleria island (Italy) hosts a high enthalpy geothermal system characterized by high CH4 and low H2S fluxes. Two selected sites, FAV1 and FAV2, located at Favara Grande, the main exhalative area of the island, show similar physical conditions with a surface temperature close to 60° C and a soil gas composition enriched in CH4, H2 and CO2. FAV1 soil is characterized by harsher conditions (pH 3.4 and 12% of H2O content); conversely, milder conditions were recorded at site FAV2 (pH 5.8 and 4% of H2O content). High methanotrophic activity (59.2 nmol g-1 h-1) and wide diversity of methanotrophic bacteria were preliminary detected at FAV2, while no activity was detected at FAV1(1). Our aim was to investigate how the soil microbial communities of these two close geothermal sites at Pantelleria island respond to different geochemical conditions. Bacterial and Archaeal communities of the sites were investigated by MiSeq Illumina sequencing of hypervariable regions of the 16S rRNA gene. More than 33,000 reads were obtained for Bacteria and Archaea from soil samples of the two sites. At FAV1 99% of the bacterial sequences were assigned to four main phyla (Proteobacteria, Firmicutes, Actinobacteria and Chloroflexi). FAV2 sequences were distributed in the same phyla with the exception of Chloroflexi that was represented below 1%. Results indicate a high abundance of thermo-acidophilic chemolithotrophs in site FAV1 dominated by Acidithiobacillus ferrooxidans (25%), Nitrosococcus halophilus (10%), Alicyclobacillus spp. (7%) and the rare species Ktedonobacter racemifer (11%). The bacterial community at FAV2 soil is dominated by

  8. The stratigraphic sequence of Scafati (Italy) - An archive of 10,000 years of volcanism, soil formation and land use in the shade of Mount Vesuvius

    NASA Astrophysics Data System (ADS)

    Maerker, Michael; Vogel, Sebastian; Hoelzmann, Phillip; Rellini, Ivano

    2014-05-01

    In this study we carried out a detailed lithostratigraphic, pedological and micromorphological analysis at a stratigraphic sequence close to Scafati, about 3 km east of ancient Pompeii. It consists of a multilayered succession of repeated volcanic deposition and pedogenesis caused by several phases of volcanic activity of Somma-Vesuvius and volcanic quiescence. This comprises, at least, the last 10,000 years of sedimentation history, on one hand, reflecting the entire spectrum of eruption types of Somma-Vesuvius from Plinian, sub-Plinian, rather small eruptions to effusive volcanic events and, on the other hand, soil formations of different durations, intensities and soil-forming environments. Furthermore, the paleosols repeatedly reveal clear evidence of anthropogenic activity by means of agriculture. Hence, a landscape evolution model was developed trying to reconstruct the last 10,000 years of volcanic activity, soil formation and land use in the hinterland of Pompeii.

  9. Radon levels in groundwaters and natural radioactivity in soils of the volcanic region of La Garrotxa, Spain.

    PubMed

    Moreno, V; Bach, J; Baixeras, C; Font, Ll

    2014-02-01

    Groundwater radon level and soil radionuclide concentration have been measured in the volcanic region of La Garrotxa (Catalonia, Spain) to further research on the origin and dynamics of high radon levels over volcanic materials found in this region. Water samples from different aquifers have been collected from wells and springs and the water radon levels obtained have been lower than 30 Bq l(-1). Soil samples have been collected from different geological formations (volcanic and non-volcanic), being Quaternary sedimentary deposits those that have presented the highest mean values of (40)K, (226)Ra and (232)Th concentrations (448 ± 70 Bq kg(-1), 35 ± 5 Bq kg(-1) and 38 ± 5 Bq kg(-1), respectively). Additionally, indoor/outdoor terrestrial radiation absorbed dose rate in air have been measured to better characterize the region from the radiological point of view. Terrestrial radiation absorbed dose rates measurement points have been chosen on the basis of geological and demographical considerations and the results obtained, from 27 to 91 nGy h(-1), show a clear relation with geological formation materials. The highest terrestrial gamma absorbed dose rate is observed over Quaternary sedimentary deposits as well. All these results help to better understand previous surveys related with indoor and outdoor radon levels and to reinforce the hypotheses of a radon transport through the fissure network.

  10. Controls on carbon storage and weathering in volcanic soils across a high-elevation climate gradient on Mauna Kea, Hawaii.

    PubMed

    Kramer, Marc G; Chadwick, Oliver A

    2016-09-01

    Volcanic ash soils retain the largest and most persistent soil carbon pools of any ecosystem. However, the mechanisms governing soil carbon accumulation and weathering during initial phases of ecosystem development are not well understood. We examined soil organic matter dynamics and soil development across a high-altitude (3,560-3,030 m) 20-kyr climate gradient on Mauna Kea in Hawaii. Four elevation sites were selected (~250-500 mm rainfall), which range from sparsely vegetated to sites that contain a mix of shrubs and grasses. At each site, two or three pits were dug and major diagnostic horizons down to bedrock (intact lava) were sampled. Soils were analyzed for particle size, organic C and N, soil pH, exchangeable cations, base saturation, NaF pH, phosphorous sorption, and major elements. Mass loss and pedogenic metal accumulation (hydroxlamine Fe, Al, and Si extractions) were used to measure extent of weathering, leaching, changes in soil mineralogy and carbon accumulation. Reactive-phase (SRO) minerals show a general trend of increasing abundance with increasing rainfall. However carbon accumulation patterns across the climate gradient are largely decoupled from these trends. The results suggest that after 20 kyr, pedogenic processes have altered the nature and composition of the volcanic ash such that it is capable of retaining soil C even where organic acid influences from plant material and leaching from rainfall are severely limited. Carbon storage comparisons with lower-elevation soils on Mauna Kea and other moist mesic (2,500 mm rainfall) sites on Hawaii suggest that these soils have reached only between 1% and 15% of their capacity to retain carbon. Our results suggest that, after 20 kyr in low rainfall and a cold climate, weathering was decoupled from soil carbon accumulation patterns and the associated influence of vegetation on soil development. Overall, we conclude that the rate of carbon supply to the subsoil (driven by coupling of rainfall

  11. Susceptibility of volcanic ash-influenced soil in Northern Idaho to mechanical compaction. Forest Service research note

    SciTech Connect

    Page-Dumroese, D.S.

    1993-02-01

    Timber harvesting and mechanical site preparation can reduce site productivity if they excessively disturb or compact the soil. Volcanic ash-influenced soils with low undisturbed bulk densities and rock content are particularly susceptible. The study evaluates the effects of harvesting and site preparation on changes in the bulk density of ash-influenced forest soils in northern Idaho. Three different levels of surface organic matter were studied. Soil samples were taken before and after harvesting to determine the extent and depth of compaction. Soil bulk densities increased significantly after extensive compaction from site preparation, especially when little logging slash and surface organic matter were left on the soil surface. As site preparation intensity increased, bulk density increased significantly at greater depths in the soil profile. Although ash-influenced soils have naturally low bulk densities, they can easily be compacted to levels that limit growth. The experimental site has been designated as part of the Forest Service's national long-term site productivity study into the impacts of organic matter depletion and soil compaction on stand development.

  12. Distinct bacterial community structure of 3 tropical volcanic soils from banana plantations contaminated with chlordecone in Guadeloupe (French West Indies).

    PubMed

    Mercier, Anne; Dictor, Marie-Christine; Harris-Hellal, Jennifer; Breeze, Dominique; Mouvet, Christophe

    2013-08-01

    In the French West Indies (FWI), the soil, andosols, ferralsols and nitisols, is highly polluted by chlordecone, although this organochlorine insecticide extensively applied to banana crops has been banned for 20years. This contamination has led to a major human health concern inducing the need for remediation of the contaminated soils. Work was conducted to help to evaluate the impact of remediation processes on the microbial communities from these soils. Microbial biomass was estimated after direct DNA extraction from three chlordecone-contaminated soils (an andosol, a ferralsol and a nitisol) and the bacterial community analyzed using t-RFLP. The FWI volcanic andosol was particularly recalcitrant to usual direct DNA extraction protocols hampering analysis of soil microbial communities until now, in contrast with the 2 other soils. For the first time, DNA was directly extracted from a FWI andosol based on yeast RNA addition at the lysis step. Differences in microbial biomass were thus observed between the 3 FWI soils. Moreover, the bacterial community structure was significantly distinct from each other's and related to soil physico-chemical characteristics. Interestingly, differences in bacterial diversity could not be exclusively attributed to the level of chlordecone contamination.

  13. Trace metal contents in wild edible mushrooms growing on serpentine and volcanic soils on the island of Lesvos, Greece.

    PubMed

    Aloupi, M; Koutrotsios, G; Koulousaris, M; Kalogeropoulos, N

    2012-04-01

    The objectives of this survey were (1) to assess for the first time the Cd, Cu, Cr, Fe, Mn, Ni, Pb and Zn contents in wild edible mushrooms (Russula delica, Lactarius sanguifluus, Lactarius semisanguifluus, Lactarius deliciosus, Suillus bellinii) from the island of Lesvos, (2) to investigate the metals' variability among the species, as well as in relation to the chemical composition of the underlying soil, comparing mushrooms collected from volcanic and serpentine substrates and (3) to estimate metal intake by the consumption of the mushrooms under consideration. The trace metals in 139 samples were determined by flame or flameless atomic absorption spectroscopy. The median metal concentrations were as follows: Cd: 0.14; Cr: 0.10; Cu: 8.51; Fe: 30.3; Mn: 5.26; Ni: 0.34; Pb: 0.093 and Zn: 64.50, all in mgkg(-1) dry weight. The observed concentrations are among the lowest reported for mushrooms from Europe or Turkey, while Pb and Cd values did not exceed the limits set by the European Union. Significant species- and substrate-related differences in the metal contents were found, but the variability did not follow a uniform pattern for all the metals in all mushroom species. As a general trend, the mushrooms growing in serpentine sites contained higher Cd, Cr and Ni than those from volcanic sites. The calculated bioconcentration factors (BCFs) showed that none of the mushrooms can be regarded as a metal bioaccumulator, although BCF values slightly above unity were found for Zn in the three Lactarius species, and for Cu in R. delica. The studied mushrooms could supply considerable amounts of essential metals such as Zn and Cr. On the other hand, the consumption of R. delica collected from volcanic soils could provide 12% of the Cd daily tolerable intake and as high as 53% when collected from serpentine soils. Nonetheless, our results indicate that the regular consumption of wild edible mushrooms from Lesvos is quite safe for human health.

  14. Long-term reactivity of lung and mediastinal lymph nodes following intratracheal instillation of sandy loam soil or Mount St. Helens volcanic ash

    SciTech Connect

    Sanders, C.L.; Rhoads, K.; Mahaffey, J.A.

    1983-01-01

    The effects of Ritzville sandy loam soil and Mount St. Helens volcanic ash particles on the lung and mediastinal lymph nodes of Fischer rats were studied about 400 days after intratracheal instillation. A total of 22 or 77 mg of soil or ash was given in two or seven equally divided, consecutive, weekly intervals as a suspension in 0.5 ml saline. Significantly elevated levels of lipid-phosphorus and protein were found in lung lavages of rats given ash compared to those given soil. An enhanced histological degree of granulomatous reactivity, lipoproteinosis, fibrosis, and bronchiolar hyperplasia was seen in ash-exposed rats as compared to soil-exposed rats. Mediastinal lymph nodes of ash-exposed rats were 8-18 times larger than those of soil-exposed rats due to abundant cellular microgranuloma formation and early fibrosis. Mount St. Helens volcanic ash is apparently more biologically reactive than soil particles commonly found in eastern Washington.

  15. Long-term reactivity of lung and mediastinal lymph nodes following intratracheal instillation of sandy loam soil or Mount St. Helens volcanic ash.

    PubMed

    Sanders, C L; Rhoads, K; Mahaffey, J A

    1983-10-01

    The effects of Ritzville sandy loam soil and Mount St. Helens volcanic ash particles on the lung and mediastinal lymph nodes of Fischer rats were studied about 400 days after intratracheal instillation. A total of 22 or 77 mg of soil or ash was given in two or seven equally divided, consecutive, weekly intervals as a suspension in 0.5 ml saline. Significantly elevated levels of lipid-phosphorus and protein were found in lung lavages of rats given ash compared to those given soil. An enhanced histological degree of granulomatous reactivity, lipoproteinosis, fibrosis, and bronchiolar hyperplasia was seen in ash-exposed rats as compared to soil-exposed rats. Mediastinal lymph nodes of ash-exposed rats were 8-18 times larger than those of soil-exposed rats due to abundant cellular microgranuloma formation and early fibrosis. Mount St. Helens volcanic ash is apparently more biologically reactive than soil particles commonly found in eastern Washington.

  16. Soil microbial structure and function post-volcanic eruption on Kasatochi Island and regional controls on microbial heterogeneity

    NASA Astrophysics Data System (ADS)

    Zeglin, L. H.; Rainey, F.; Wang, B.; Waythomas, C.; Talbot, S. L.

    2013-12-01

    Microorganisms are abundant and diverse in soil and their integrated activity drives nutrient cycling on the ecosystem scale. Organic matter (OM) inputs from plant production support microbial heterotrophic life, and soil geochemistry constrains microbial activity and diversity. As vegetation and soil develops over time, these factors change, modifying the controls on microbial heterogeneity. Following a volcanic eruption, ash deposition creates new surfaces where both organismal growth and weathering processes are effectively reset. The trajectory of microbial community development following this disturbance depends on both organic matter accumulation and geochemical constraints. Also, dispersal of microbial cells to the sterile ash surface may determine microbial community succession. The Aleutian Islands (Alaska, USA) are a dynamic volcanic region, with active and dormant volcanoes distributed across the volcanic arc. One of these volcanoes, Kasatochi, erupted violently in August 2008, burying a small lush island in pryoclastic flows and fine ash. Since, plants and birds are beginning to re-establish on developing surfaces, including legacy soils exposed by rapid erosion of pyroclastic deposits, suggesting that recovery of microbial life is also proceeding. However, soil microbial diversity and function has not been examined on Kasatochi Island or across the greater Aleutian region. The project goal is to address these questions: How is soil microbial community structure and function developing following the Kasatochi eruption? What is the relative importance of dispersal, soil OM and geochemistry to microbial community heterogeneity across the Aleutians? Surface mineral soil (20-cm depth) samples were collected from Kasatochi Island in summer 2013, five years after the 2008 eruption, and from eight additional Aleutian islands. On Kasatochi, pryoclastic deposits, exposed legacy soils supporting regrowth of remnant dune wild-rye (Leymus mollis) and mesic meadow

  17. Effect of long-term different fertilization on bacterial community structures and diversity in citrus orchard soil of volcanic ash.

    PubMed

    Joa, Jae Ho; Weon, Hang Yeon; Hyun, Hae Nam; Jeun, Young Chull; Koh, Sang Wook

    2014-12-01

    This study was conducted to assess bacterial species richness, diversity and community distribution according to different fertilization regimes for 16 years in citrus orchard soil of volcanic ash. Soil samples were collected and analyzed from Compost (cattle manure, 2,000 kg/10a), 1/2 NPK+compost (14-20-14+2,000 kg/10a), NPK+compost (28-40-28+2,000 kg/10a), NPK (28-40-28 kg/10a), 3 NPK (84-120-84 kg/10a), and Control (no fertilization) plot which have been managed in the same manners with compost and different amount of chemical fertilization. The range of pyrosequencing reads and OTUs were 4,687-7,330 and 1,790-3,695, respectively. Species richness estimates such as Ace, Chao1, and Shannon index were higher in 1/2 NPK+compost than other treatments, which were 15,202, 9,112, 7.7, respectively. Dominant bacterial groups at level of phylum were Proteobacteria, Acidobacteria, and Actinobacteria. Those were occupied at 70.9% in 1/2 NPK+compost. Dominant bacterial groups at level of genus were Pseudolabrys, Bradyrhizobium, and Acidobacteria. Those were distributed at 14.4% of a total of bacteria in Compost. Soil pH displayed significantly closely related to bacterial species richness estimates such as Ace, Chao1 (p<0.05) and Shannon index (p<0.01). However, it showed the negative correlation with exchangeable aluminum contents (p<0.05). In conclusion, diversity of bacterial community in citrus orchard soil was affected by fertilization management, soil pH changes and characteristics of volcanic ash.

  18. Lichen-rock interaction in volcanic environments: evidences of soil-precursor formation

    NASA Astrophysics Data System (ADS)

    Vingiani, S.; Adamo, P.; Terribile, F.

    2012-04-01

    The weathering action of the lichens Lecidea fuscoatra (L.) Ach. and Stereocaulon vesuvianum Pers. on basaltic rock collected on the slopes of Mt. Etna (Sicily) at 1550 m a.s.l. has been studied using optical (OM) and electron (SEM) microscopy equipped with microanalytical device (EDS). Biological factors associated with lichen growth play a major role in the weathering of minerals on bare rocks and contribute to the preliminary phases of soil formation. The present work investigates the biogeophysical and biogeochemical weathering associated to the growth of epilithic lichens on lava flows from Mt. Etna (Sicily) and Mt. Vesuvius (Campania). The chosen lichen species were the crustose Lecidea fuscoatra (L.) Ach., the foliose Xanthoparmelia conspersa and the fructicose Stereocaulon vesuvianum Pers. An integrated approach based on the study of both disturbed and undisturbed samples of lichenized rock was applied in order to appreciate the complexity of the rock-lichen interface environment in terms of micromorphological, mineralogical and chemical properties. XRD and XRF analyses coupled to microscopical (OM), submicroscopical (SEM) and microanalitical (EDS) observations were the used techniques. In both study environments, the chemical, mineralogical and micromorphological properties of the uncoherent materials found at the lichen-rock interface suggest they consist of rock fragments eroded from the surroundings and accumulated in cavities and fissures of the rough lava flows. According to the thallus morphology, the lichens colonizing the lava preserve the interface materials from further aeolic and water erosion, provide these materials of organic matter and moisture, entrap allochtonous quartz and clay minerals. The calcium oxalate production by L. fuscoatra and X. conspersa, the Al enrichment around S. vesuvianum hyphae and the occurrence of Fe-oxide phases at the rock-lichen interface are evidences of lichens interaction with the underlying sediments. Indeed

  19. Effects of seagulls on ecosystem respiration, soil nitrogen and vegetation cover on a pristine volcanic island, Surtsey, Iceland

    NASA Astrophysics Data System (ADS)

    Sigurdsson, B. D.; Magnusson, B.

    2010-03-01

    When Surtsey rose from the North Atlantic Ocean south of Iceland in 1963, it became a unique natural laboratory on how organisms colonize volcanic islands and form ecosystems with contrasting structures and functions. In July, 2004, ecosystem respiration rate (Re), soil properties and surface cover of vascular plants were measured in 21 permanent research plots distributed among the juvenile communities of the island. The plots were divided into two main groups, inside and outside a seagull (Larus spp.) colony established on the island. Vegetation cover of the plots was strongly related to the density of gull nests. Occurrence of nests and increased vegetation cover also coincided with significant increases in Re, soil carbon, nitrogen and C:N ratio, and with significant reductions in soil pH and soil temperatures. Temperature sensitivity (Q10 value) of Re was determined as 5.3. When compared at constant temperature the Re was found to be 59 times higher within the seagull colony, similar to the highest fluxes measured in drained wetlands or agricultural fields in Iceland. The amount of soil nitrogen, mainly brought onto the island by the seagulls, was the critical factor that most influenced ecosystem fluxes and vegetation development on Surtsey. The present study shows how ecosystem activity can be enhanced by colonization of animals that transfer resources from a nearby ecosystem.

  20. The association of endemic elephantiasis of the lower legs in East Africa with soil derived from volcanic rocks.

    PubMed

    Price, E W

    1976-01-01

    Endemic elephantiasis of the lower legs in Ethiopia, which reaches a maximum of 86-7 per 1,000 adults in affected areas, is related to the distribution of red clay soil derived from volcanic rocks, particularly basalt. Prevalence falls rapidly on leaving these areas. This observation has been tested in regions of non-filarial elephantiasis reported in Kanya and north-western Tanzania and further investigated in volcanic areas of Rwanda where the disease had not previously been reported. The same relationship is found to occur in these areas. The limitation to the lower legs of the barefooted section of the farming community suggests that the aetiological factor or factors enter by the feet. The occurrence at high altitude (over 1,200 metres) is noted and the predominance of basalt or basalt-like lava in each case is considered significant. The altitude governs rainfall and temperature and thus governs the type of soil produced. The soil produced from these rocks is rich in colloidal iron oxide, alumina and silica, to which a number of metallic ions are adsorbed. This soil is a reddish-brown clay which, when wet, is strongly adherent to the skin. The derived ions are known to be toxic to human tissue and absorption through intact human skin has been shown to occur experimentally. It is suggested that absorption of these irritants through the bare feet is responsible for the irreversible damage to the lymphatic channels. The present studies support the hypothesis that "high-altitude" elephantiasis of the lower legs in East Africa is a geochemical disease.

  1. Land use and Hydrological Characteristics of Volcanic Urban Soils for Flood Susceptibility Modeling, Ciudad de Colima (Mexico)

    NASA Astrophysics Data System (ADS)

    Perez Gonzalez, M. L.; Capra, L.; Borselli, L.; Ortiz, A.

    2015-12-01

    The fast population rate growth and the unplanned urban development has created an increase of urban floods in the City of Colima. Land use change has transformed the hydrological behavior of the watersheds that participates on the runoff-infiltration processes that governs the pluvial concentrations. After the urban areas enlargement, 13% from 2010 to 2015, rainfall has caused significant damages to the downtown community. Therefore it is important to define the main hydraulic properties of the soils surrounding the city. The soil of the region is derived from the debris avalanche deposits of the Volcano of Colima. The volcanic soil cover is only 10 to 15 cm depth. To test the soils of the region, sampling locations were chosen after making a land use map from a Landsat image. The map was done by selecting and dividing similar surface images patterns into three main classifications: Natural (N1), Agricultural (N5) and Urban (N4) surfaces. Thirty-Three soil samples were collected and grouped in nine out of ten land use subdivisions. The 10thsubdivision, represents the completed urbanized area. The land use model is made using spot 4 1A images from the year 2010 up to year 2015. This land use evolutionary analysis will be a base to evaluate the change of the runoff-infiltration rate, direction, and concentration areas for the future flood susceptibility model. To get the parameters above, several soil analysis were performed. The results were that all the soil samples tested were classified as sandy soils. The water content values were from 7% (N4) to 45% (N1) while bulk density values for the same sample were form 0.65 (N1) to 1.50 (N4) g/cm3. The particle density and the porosity values were from 1.65 g/cm3 /5.5% (N4) - 2.65 g/cm3/ 75.40% (N1). The organic matter content was around 0.1% for urban soils and up to 6% on natural and agricultural soils. Some other test like electric conductivity and pH were performed. The obtained parameters were used to get other

  2. Relationship between regional changes of soil physical properties and volcanic stratigraphy on the southern slope of Batur volcano in the island of Bali, Indonesia

    NASA Astrophysics Data System (ADS)

    Tanaka, T.; Sunarta, N.

    1994-04-01

    The present paper shows the relationship between the regional changes of soil physical properties and the volcanic stratigraphy on the southern slope of Batur volcano in the island of Bali, Indonesia, from the hydrogeological point of view based on the data obtained from field observations and laboratory experiments. The Bali soils data showed marked differences in regional distribution and their characteristics are closely correlated to the distribution of the volcanic stratigraphy derived from the Batur volcanic activities with the eruption about 23,700 years ago. On the basis of these data, the hydrogeological situation of the slope are presented schematically and groundwater flow regimes on the slope, such as recharge and discharge areas, are also classified according to the hydrogeological information. These classifications of groundwater flow regimes are useful to consider the occurrence of hydrological phenomena such as springs and paddy field distributions observed on the slope.

  3. Strontium isotopes provide clues for a process shift in base cation dynamics in young volcanic soils

    NASA Astrophysics Data System (ADS)

    Bingham, N.; Jackson, M. G.; Bookhagen, B.; Maher, K.; Chadwick, O.

    2015-12-01

    Despite advances in soil development theory based on studies of old soils or over long timescales, little is known about soil thresholds (dramatic changes in soil properties associated with only small shifts in external forcing factors) that might be expressed in young soils (less than 10 kyr). Therefore, we seek to understand infant soil development in a tropical environment through the sourcing of plant available base cations by measuring the strontium (Sr) isotopic composition of the soil exchange complex. Our sampling strategy spans soils in three different precipitation ranges (950-1060 mm, 1180-1210 mm, and 1450-1500) and an array of soil ages from 500 to 7500 years in the Kona region on the island of Hawaii. In Hawaiian soils, 87Sr/86Sr values are determined by a mixture of three components: a mantle-derived component from the lava (0.7034), a rainfall component (0.7093) and a component from continental dust (0.720). Elevation-controlled leaching intensity in the wettest localities produces a decline in the concentration of base cations supplied by basalt and a dilute resupply by rainfall. In the driest sites, where leaching intensity is dramatically reduced, there is a buildup of rainfall-derived extractable Sr in the soil over time. Slow rock weathering rates produce a small rock-derived cation input to the soil. Thus, Sr isotope signatures reflect both the input of rainfall-derived cations and rock-derived cations with values that fall between rainfall and basaltic signatures. Soils in the intermediate precipitation range have Sr isotopic signatures consistent with both the wet and dry trends; suggesting that they lie close to the critical precipitation amount that marks a shift between these two processes. For the Kona region, this transition seems to occur at 1200 mm /yr. In contrast to the clear-cut differentiation in strontium isotopes with precipitation shifts observed in older soils, patterns on these young soils in Kona are complicated by low soil

  4. Hardening of the arteries

    MedlinePlus

    Atherosclerosis; Arteriosclerosis; Plaque buildup - arteries; Hyperlipidemia - atherosclerosis; Cholesterol - atherosclerosis ... cause of heart attack and stroke. High blood cholesterol levels can cause hardening of the arteries at ...

  5. Rare earth elements distribution in grapevine varieties grown on volcanic soils: an example from Mount Etna (Sicily, Italy).

    PubMed

    D'Antone, Carmelisa; Punturo, Rosalda; Vaccaro, Carmela

    2017-04-01

    A geochemical and statistical approach has allowed identifying in rare earth elements (REEs) absorption a good fingerprinting mark for determining the territoriality and the provenance of Vitis vinifera L. in the district of Mount Etna (southern Italy). Our aim is to define the REEs distribution in different parts of the plants which grow in the same volcanic soil and under the same climate conditions, and therefore to assess whether REEs distribution may reflect the composition of the provenance soil or if plants can selectively absorb REEs in order to recognize the fingerprint in the Etna Volcano soils as well as the REEs pattern characteristic of each cultivar of V. vinifera L. The characteristic pattern of REEs has been determined by ICP-MS analyses in the soils and in the selected grapevine varieties for all the following parts: leaves, seeds, juice, skin, and berries. These geochemical criteria, together with the multivariate statistical analysis of the principal component analysis (PCA) and of the linear discriminant analysis (LDA) that can be summarized with the box plot, suggest that leaves mostly absorb REEs than the other parts of the plant. This work investigates the various parts of the plant in order to verify if each grape variety presents a characteristic geochemical pattern in the absorption of REEs in relationship with the geochemical features of the soil so to highlight the individual compositional fingerprint. Based on REE patterns, our study is a useful tool that allows characterizing the differences among the grape varieties and lays the foundation for the use of REEs in the geographic origin of the Mount Etna wine district.

  6. Ammonia emission from a permanent grassland on volcanic soil after the treatment with dairy slurry and urea

    NASA Astrophysics Data System (ADS)

    Salazar, F.; Martínez-Lagos, J.; Alfaro, M.; Misselbrook, T.

    2014-10-01

    Ammonia (NH3) is an air pollutant largely emitted from agricultural activities including the application of livestock manures and fertilizers to grassland. This gas has been linked with important negative impacts on natural ecosystems. In southern Chile, the use of inorganic and organic fertilizers (e.g. slurries) has increased in cattle production systems over recent years, heightening the risk of N losses to the wider environment. The objectives of this study were to evaluate on permanent grasslands on a volcanic ash soil in southern Chile: 1) the N loss due to NH3 volatilization following surface application of dairy slurry and urea fertilizer; and 2) the effect of a urease inhibitor on NH3 emissions from urea fertilizer application. Small plot field experiments were conducted over spring, fall, winter and summer seasons, using a system of wind tunnels to measure ammonia emissions. Ammonia losses ranged from 1.8 (winter) to 26.0% (fall) and 3.1 (winter) to 20.5% (summer) of total N applied for urea and slurry, respectively. Based on the readily available N applied (ammoniacal N for dairy slurry and urea N for urea fertilizer), losses from dairy slurry were much greater, at 16.1 and 82.0%, for winter and summer, respectively. The use of a urease inhibitor proved to be an effective option to minimize the N loss due NH3 volatilization from urea fertilizer, with an average reduction of 71% across all seasons. The results of this and other recent studies regarding N losses suggest that ammonia volatilization is the main pathway of N loss from grassland systems in southern Chile on volcanic ash soils when urea and slurry are used as an N source. The use of good management practices, such as the inclusion of a urease inhibitor with urea fertilizer could have a beneficial impact on reducing N losses due NH3 volatilization and the environmental and economic impact of these emissions.

  7. Carbon flow from volcanic CO2 into soil microbial communities of a wetland mofette.

    PubMed

    Beulig, Felix; Heuer, Verena B; Akob, Denise M; Viehweger, Bernhard; Elvert, Marcus; Herrmann, Martina; Hinrichs, Kai-Uwe; Küsel, Kirsten

    2015-03-01

    Effects of extremely high carbon dioxide (CO2) concentrations on soil microbial communities and associated processes are largely unknown. We studied a wetland area affected by spots of subcrustal CO2 degassing (mofettes) with focus on anaerobic autotrophic methanogenesis and acetogenesis because the pore gas phase was largely hypoxic. Compared with a reference soil, the mofette was more acidic (ΔpH ∼0.8), strongly enriched in organic carbon (up to 10 times), and exhibited lower prokaryotic diversity. It was dominated by methanogens and subdivision 1 Acidobacteria, which likely thrived under stable hypoxia and acidic pH. Anoxic incubations revealed enhanced formation of acetate and methane (CH4) from hydrogen (H2) and CO2 consistent with elevated CH4 and acetate levels in the mofette soil. (13)CO2 mofette soil incubations showed high label incorporations with ∼512 ng (13)C g (dry weight (dw)) soil(-1) d(-1) into the bulk soil and up to 10.7 ng (13)C g (dw) soil(-1) d(-1) into almost all analyzed bacterial lipids. Incorporation of CO2-derived carbon into archaeal lipids was much lower and restricted to the first 10 cm of the soil. DNA-SIP analysis revealed that acidophilic methanogens affiliated with Methanoregulaceae and hitherto unknown acetogens appeared to be involved in the chemolithoautotrophic utilization of (13)CO2. Subdivision 1 Acidobacteriaceae assimilated (13)CO2 likely via anaplerotic reactions because Acidobacteriaceae are not known to harbor enzymatic pathways for autotrophic CO2 assimilation. We conclude that CO2-induced geochemical changes promoted anaerobic and acidophilic organisms and altered carbon turnover in affected soils.

  8. On shakedown analysis in hardening plasticity

    NASA Astrophysics Data System (ADS)

    Nguyen, Quoc-Son

    2003-01-01

    The extension of classical shakedown theorems for hardening plasticity is interesting from both theoretical and practical aspects of the theory of plasticity. This problem has been much discussed in the literature. In particular, the model of generalized standard materials gives a convenient framework to derive appropriate results for common models of plasticity with strain-hardening. This paper gives a comprehensive presentation of the subject, in particular, on general results which can be obtained in this framework. The extension of the static shakedown theorem to hardening plasticity is presented at first. It leads by min-max duality to the definition of dual static and kinematic safety coefficients in hardening plasticity. Dual static and kinematic approaches are discussed for common models of isotropic hardening of limited or unlimited kinematic hardening. The kinematic approach also suggests for these models the introduction of a relaxed kinematic coefficient following a method due to Koiter. Some models for soils such as the Cam-clay model are discussed in the same spirit for applications in geomechanics. In particular, new appropriate results concerning the variational expressions of the dual kinematic coefficients are obtained.

  9. Steels with controlled hardenability for induction hardening

    NASA Astrophysics Data System (ADS)

    Shepelyakovskii, K. Z.

    1980-07-01

    Steels of the CH and LH type developed in the Soviet Union permit the use of a new method of induction hardening — bulk-surface hardening — and efficient utilization of the high-strength conditions (σb = 230-250 kgf/mm2). These steels make it possible to improve the structural strength, operating characteristics, service life, and reliability of critical heavily loaded machine parts. At the same time, CH steels make it possible to reduce by a factor of 2-3 the quantity of alloying elements, reduce the electrical energy for heat treatment, and completely exclude the cost of quenching oil for heat treatment in automatic equipment with high labor productivity, while retaining good working conditions. All this leads to substantial savings in production and operation. For example, when transmission gears (cylindrical and conical) are manufactured from LH steels the annual savings amount to more than 700,000 rubles at two automobile plants. Machine parts of CH steels — half axles and bearings in railway cars —have saved respectively six and four million rubles annually. The introduction of controlled-hardenability steels for induction hardening is a necessary condition for technological progress in machine construction and metallurgy.

  10. Exploring a long-lasting volcanic eruption by means of in-soil radon measurements and seismic activity

    NASA Astrophysics Data System (ADS)

    Falsaperla, Susanna; Neri, Marco; Di Grazia, Giuseppe; Langer, Horst; Spampinato, Salvatore

    2016-04-01

    We analyze in-soil radon (Rn) emission and ambient parameters (barometric pressure and air temperature measurements) along with seismic activity during the longest flank eruption of this century at Mt. Etna, Italy. This eruption occurred between 14 May 2008 and 6 July 2009, from a N120-140°E eruptive fissure extending between 3050 and 2620 m above sea level. It was heralded by a short-lived (~5 hours) episode of lava fountaining three days before a dike-forming intrusion fed a lava emission, which affected the summit area of the volcano over ~15 months. The peculiar position of the station for the Rn measurement, which was at an altitude of 2950 m above sea level and near (~1 km) the summit active craters, offered us the uncommon chance: i) to explore the temporal development of the gas emission close (<2 km) to the 2008-2009 eruptive vents in the long term, and ii) to analyze the relationship between in-soil Rn fluxes and seismic signals (in particular, local earthquakes and volcanic tremor) during the uninterrupted lava emission. This approach reveals important details about the recharging phases characterizing the 2008-2009 eruption, which are not visible with other methods of investigation. Our study benefitted from the application of methods of pattern classification developed in the framework of the European MEDiterrranean Supersite Volcanoes (MED­SUV) project.

  11. Carbon flow from volcanic CO2 into soil microbial communities of a wetland mofette

    USGS Publications Warehouse

    Beulig, Felix; Heuer, Verena B.; Akob, Denise M.; Viehweger, Bernhard; Elvert, Marcus; Herrmann, Martina; Hinrichs, Kai-Uwe; Küsel, Kirsten

    2015-01-01

    Effects of extremely high carbon dioxide (CO2) concentrations on soil microbial communities and associated processes are largely unknown. We studied a wetland area affected by spots of subcrustal CO2 degassing (mofettes) with focus on anaerobic autotrophic methanogenesis and acetogenesis because the pore gas phase was largely hypoxic. Compared with a reference soil, the mofette was more acidic (ΔpH ~0.8), strongly enriched in organic carbon (up to 10 times), and exhibited lower prokaryotic diversity. It was dominated by methanogens and subdivision 1Acidobacteria, which likely thrived under stable hypoxia and acidic pH. Anoxic incubations revealed enhanced formation of acetate and methane (CH4) from hydrogen (H2) and CO2 consistent with elevated CH4 and acetate levels in the mofette soil. 13CO2 mofette soil incubations showed high label incorporations with ~512 ng13C g (dry weight (dw)) soil−1 d−1 into the bulk soil and up to 10.7 ng 13C g (dw) soil−1 d−1 into almost all analyzed bacterial lipids. Incorporation of CO2-derived carbon into archaeal lipids was much lower and restricted to the first 10 cm of the soil. DNA-SIP analysis revealed that acidophilic methanogens affiliated withMethanoregulaceae and hitherto unknown acetogens appeared to be involved in the chemolithoautotrophic utilization of 13CO2. Subdivision 1 Acidobacteriaceae assimilated 13CO2 likely via anaplerotic reactions because Acidobacteriaceae are not known to harbor enzymatic pathways for autotrophic CO2 assimilation. We conclude that CO2-induced geochemical changes promoted anaerobic and acidophilic organisms and altered carbon turnover in affected soils.

  12. Dissolved Organic Matter as a Mechanism for Carbon Stabilization at Depth in Wet Tropical Forest Volcanic Soils

    NASA Astrophysics Data System (ADS)

    Marin-Spiotta, E.; Kramer, M. G.; Chadwick, O. A.

    2007-12-01

    Dissolved organic matter (DOM) plays an important role in many biological and chemical processes in soils. Our understanding of the types of plant and microbially-derived organic matter that accumulate in soils and the mechanisms responsible for their transformation and stabilization is still limited. In particular, we know very little about how microbial activity and water movement contribute to the production of DOM and the formation of stable C in soils. In well-drained soils under wet climates, DOM is potentially a primary pathway for the transport of C from the surface litter layers and the zones of highest microbial activity to deeper horizons in the soil profile where the potential for long-term storage increases. The mechanisms for long-term stabilization of organic C in deep mineral horizons include an accumulation of chemically recalcitrant C, strong sorption of soluble and otherwise labile C to mineral and/or metals making them inaccessible to decomposers, and microenvironmental conditions (low pH, low O2) which result in incomplete decomposition and persistence of labile C. Although most work to date has focused on the role of dissolved organic C and N (DOC and DON) in the C and N cycles of temperate forests, DOM fluxes may be even more important in forests in the wet tropics, where high rainfall and high primary productivity could lead to greater DOM production. In order to address the role of DOC in the transport and stabilization of C in mineral horizons, we are studying DOC production, transformation, and loss pathways in volcanic soils dominated by highly reactive, non-crystalline minerals (allophane). We are quantifying flux and solute concentrations (C, N, cations, anions) in rainwater, throughfall, and in soil water. We have installed tension and zero tension lysimeters throughout sequentially deeper organic and mineral horizons in an intermediate aged soil (ca. 350k years) under wet (ca. 3000 mm mean annual rainfall) native tropical forest

  13. Ammonia-limited conditions cause of Thaumarchaeal dominance in volcanic grassland soil.

    PubMed

    Daebeler, Anne; Bodelier, Paul L E; Hefting, Mariet M; Laanbroek, Hendrikus J

    2015-03-01

    The first step of nitrification is carried out by ammonia-oxidizing bacteria (AOB) and archaea (AOA). It is largely unknown, by which mechanisms these microbes are capable of coexistence and how their respective contribution to ammonia oxidation may differ with varying soil characteristics. To determine how different levels of ammonium availability influence the extent of archaeal and bacterial contributions to ammonia oxidation, microcosm incubations with controlled ammonium levels were conducted. Net nitrification was monitored and ammonia-oxidizer communities were quantified. Additionally, the nitrification inhibitor allylthiourea (ATU) was applied to discriminate between archaeal and bacterial contributions to soil ammonia oxidation. Thaumarchaeota, which were the only ammonia oxidizers detectable at the start of the incubation, grew in all microcosms, but AOB later became detectable in ammonium amended microcosms. Low and high additions of ammonium increasingly stimulated AOB growth, while AOA were only stimulated by the low addition. Treatment with ATU had no effect on net nitrification and sizes of ammonia-oxidizing communities suggesting that the effective concentration of ATU to discriminate between archaeal and bacterial ammonia oxidation is not the same in different soils. Our results support the niche-differentiating potential of ammonium concentration for AOA and AOB, and we conclude that ammonium limitation can be a major reason for absence of detectable AOB in soil.

  14. Hardening: Australian for Transformation

    DTIC Science & Technology

    2004-01-01

    ADF towards homeland defense. For further details, see Jeffrey Grey. A Military History of Australia. Melbourne, Australia, Cambridge University...is a simplified explanation of the hardene d force structure proposed by FLW. The hardened concept encompasses other aspects that enhance Army...standardized with three rifle companies. A 196 Leahy “ A Land Force for the Future: The Australian Army in the Early 21st Century.” 2003: 19. 197 See Monk, Paul

  15. Bacillus shackletonii sp. nov., from volcanic soil on Candlemas Island, South Sandwich archipelago.

    PubMed

    Logan, Niall A; Lebbe, Liesbeth; Verhelst, An; Goris, Johan; Forsyth, Gillian; Rodríguez-Díaz, Marina; Heyndrickx, Marc; De Vos, Paul

    2004-03-01

    A sample of mossy soil taken from the eastern lava flow of northern Candlemas Island, South Sandwich archipelago, yielded six isolates of aerobic, endospore-forming bacteria. Miniaturized routine phenotypic tests and other observations, amplified rDNA restriction analysis and SDS-PAGE analysis suggested that the strains represent a novel taxon. 16S rDNA sequence comparisons support the proposal of a novel species, Bacillus shackletonii sp. nov., the type strain of which is LMG 18435(T) (=CIP 107762(T)).

  16. Chemical element accumulation in tree bark grown in volcanic soils of Cape Verde-a first biomonitoring of Fogo Island.

    PubMed

    Marques, Rosa; Prudêncio, Maria Isabel; Freitas, Maria do Carmo; Dias, Maria Isabel; Rocha, Fernando

    2015-10-03

    Barks from Prosopis juliflora (acacia) were collected in 12 sites of different geological contexts over the volcanic Fogo Island (Cape Verde). Elemental contents of Ba, Br, Co, Cr, Fe, K, Na, Zn and some rare earth elements (REE)-La, Ce, Sm, Eu, Tb, Yb, and Lu, were obtained for biological samples and topsoils by using k 0-standardized and comparative method of instrumental neutron activation analysis (INAA), aiming the evaluation of chemical elements uptake by acacia bark. This first biomonitoring study of Fogo Island showed that, in general, significant accumulations of trace elements present in high amounts in these soils occur. This can be partially explained by the semi-arid climate with a consequent bioavailability of chemical elements when rain drops fall in this non-polluted environment. REE enrichment factors (EFs) increase with the decrease of ionic radius. Heavy REE (HREE) are significantly enriched in bark, which agrees with their release after the primary minerals breakdown and the formation of more soluble compounds than the other REE, and uptake by plants. Among the potential harmful chemical elements, Cr appears to be partially retained in nanoparticles of iron oxides. The high EFs found in tree barks of Fogo Island are certainly of geogenic origin rather than anthropogenic input since industry and the use of fertilizers is scarce.

  17. Nitrogen transformations following tropical forest felling and burning on a volcanic soil

    NASA Technical Reports Server (NTRS)

    Matson, Pamela A.; Vitousek, Peter M.; Ewel, John J.; Mazzarino, Maria Julia; Robertson, G. Philip

    1987-01-01

    Nitrogen transformations and loss were measured following forest clearing in a relatively fertile tropical forest site. Nitrogen mineralization, nitrification, and amounts of ammonium and nitrate increased substantially in surface soils during the 6 mo following burning, then returned to background levels. The nitrogen content of microbial biomass declined to half its original value 6 mo after clearing and remained low in the cleared sites. Plant uptake of nitrogen was substantial on cleared plots (50 g/sq m), but it accounted for only 18 percent of N-15 label added to field plots. MIcrobial immobilization of N-15 was small relative to that in a cleared temperate site, and measurements of denitrification potentials suggested that relatively little mineralized nitrogen was lost to the atmosphere. Substantial amounts of nitrogen (40-70 g/sq m) were retained as exchangeably bound nitrate deep in the soils of a cleared plot on which revegetation was prevented; this process accounted for 12 percent of the N-15 label added to field plots.

  18. Interactions between Thaumarchaea, Nitrospira and methanotrophs modulate autotrophic nitrification in volcanic grassland soil.

    PubMed

    Daebeler, Anne; Bodelier, Paul L E; Yan, Zheng; Hefting, Mariet M; Jia, Zhongjun; Laanbroek, Hendrikus J

    2014-12-01

    Ammonium/ammonia is the sole energy substrate of ammonia oxidizers, and is also an essential nitrogen source for other microorganisms. Ammonia oxidizers therefore must compete with other soil microorganisms such as methane-oxidizing bacteria (MOB) in terrestrial ecosystems when ammonium concentrations are limiting. Here we report on the interactions between nitrifying communities dominated by ammonia-oxidizing archaea (AOA) and Nitrospira-like nitrite-oxidizing bacteria (NOB), and communities of MOB in controlled microcosm experiments with two levels of ammonium and methane availability. We observed strong stimulatory effects of elevated ammonium concentration on the processes of nitrification and methane oxidation as well as on the abundances of autotrophically growing nitrifiers. However, the key players in nitrification and methane oxidation, identified by stable-isotope labeling using (13)CO2 and (13)CH4, were the same under both ammonium levels, namely type 1.1a AOA, sublineage I and II Nitrospira-like NOB and Methylomicrobium-/Methylosarcina-like MOB, respectively. Ammonia-oxidizing bacteria were nearly absent, and ammonia oxidation could almost exclusively be attributed to AOA. Interestingly, although AOA functional gene abundance increased 10-fold during incubation, there was very limited evidence of autotrophic growth, suggesting a partly mixotrophic lifestyle. Furthermore, autotrophic growth of AOA and NOB was inhibited by active MOB at both ammonium levels. Our results suggest the existence of a previously overlooked competition for nitrogen between nitrifiers and methane oxidizers in soil, thus linking two of the most important biogeochemical cycles in nature.

  19. Late Pleistocene to Holocene soil development and environments in the Long Gang Volcanic Field area, Jilin Province, NE China

    NASA Astrophysics Data System (ADS)

    Sauer, Daniela; Zhang, Xinrong; Knöbel, Jette; Maerker, Lutz

    2014-05-01

    Late Pleistocene to Holocene shifts of climate and vegetation in the Long Gang Volcanic Field in NE China have been reconstructed, e. g. by Steblich et al. (2009), based on Maar lake sediment cores. In this study, we investigated soil development during the Late Pleistocene and Holocene and linked it to the climate and vegetation reported in the literature. Three pedons were described and analyzed on a crater wall surrounding a maar. The lower part of the slope is covered by basic pyroclastics that are obviously younger than the maar itself. Pedon 1 is located on the upper slope, where the younger pyroclastics are not present; thus it developed over the entire Holocene and part of the Late Pleistocene. Pedon 2 is on the toe slope and developed from the young basic pyroclastics. Vegetation remains, charred by fire that was caused by the volcanic ash fall, were found in the lowermost part of the pyroclastics layer, on top of a paleosol. Charcoal fragments were dated to 18950-18830 cal BP (using INTCAL 09). Thus, pedon 2 developed since around 18.9 ka BP, whereas the development of the paleosol that was buried under the pyroclastics (pedon 3), was stopped at this time. Pedons 1 and 2 are Vitric Andosols, developed mainly from basic pyroclastics, as evidenced by the composition of rock fragments in the soils, comprising 78 / 81 mass % lapilli and 22 / 19 mass % gneiss fragments, respectively. Pedon 3 is a Cutanic Luvisol (Chromic) that developed entirely from gneiss fragments produced by the maar explosion. Lab data suggest increasing intensity of pedogenesis in the direction: Pedon 3 (paleosol) < Pedon 2 < Pedon 1, reflected e. g. in increasing Fed/Fet ratios, decreasing molar ratios of (Ca+K+Na)/Al, and decreasing pH. However, it needs to be considered that lapilli are more readily weatherable than gneiss fragments. The profile morphology of the paleosol, characterized by reddish-brown color (7.5YR), strong angular blocky structure and well-expressed illuvial clay

  20. Ammonia volatilization following dairy slurry application to a permanent grassland on a volcanic soil

    NASA Astrophysics Data System (ADS)

    Martínez-Lagos, J.; Salazar, F.; Alfaro, M.; Misselbrook, T.

    2013-12-01

    Agriculture is the largest source of ammonia (NH3) emission to the atmosphere. Within the agricultural sector, the application of slurry to grasslands as fertilizer is one of the main emission sources. This is a common practice in southern Chile, where most dairy production systems are grazing-based. In Chile, there are few published data of gaseous emissions following slurry application to grassland. The aim of this study was to evaluate NH3 volatilization following dairy slurry application to a permanent grassland on an Andosol soil. Ammonia volatilization was measured in four field experiments (winters of 2009 and 2011 and early and late springs of 2011) using a micrometeorological mass balance method with passive flux samplers following dairy slurry application at a target rate of 100 kg total N ha-1. The accumulated N loss was equivalent to 7, 8, 16 and 21% of the total N applied and 22, 34, 88 and 74% of total ammoniacal nitrogen (TAN) applied for winters 2009 and 2011, and early and late spring 2011, respectively. Ammonia emission rates were high immediately after application and declined rapidly with time, with more than 50% of the total emissions within the first 24 h. Losses were highly influenced by environmental conditions, increasing with temperature and lack of rainfall. Taking into consideration the low N losses via leaching and nitrous oxide emissions reported for the study area, results indicate that NH3 volatilization is the main pathway of N loss in fertilized grasslands of southern Chile. However, dairy slurry application could be an important source of nutrients, if applied at a suitable time, rate and using an appropriate technique, and if soil and climate conditions are taken into consideration. This could improve N use efficiency and reduce N losses to the wider environment.

  1. Volcanic Gas

    MedlinePlus

    ... Hazards Tephra/Ash Lava Flows Lahars Volcanic Gas Climate Change Pyroclastic Flows Volcanic Landslides Preparedness Volcano Hazard Zones ... Please see our discussion of volcanic gases and climate change for additional information. Hydrogen sulfide (H 2 S) is ...

  2. 42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN AND TEMPER THE NAILS; WEST TUBES IN FOREGRPUND AND DRAWBACK TUBE IN THE CENTER - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

  3. Ecosystem respiration, vegetation development and soil nitrogen in relation to breeding density of seagulls on a pristine volcanic island, Surtsey, Iceland

    NASA Astrophysics Data System (ADS)

    Sigurdsson, B. D.; Magnusson, B.

    2009-08-01

    Since its birth in 1963 by volcanic eruption in the North Atlantic Ocean off Iceland, Surtsey has been a unique natural laboratory on how organisms colonize volcanic islands and form ecosystems with contrasting structure and function. In July, 2004, ecosystem respiration rate, soil properties and surface cover of vascular plants were measured on 21 plots distributed among the main plant communities found 40 years after the primary succession started. The plots could be divided into two groups, inside and outside seagull (Larus sp.) colonies found on the island. Vegetation cover of the plots was strongly related to the density of seagull nests within and around them. The occurrence of seagull nests and increased vegetation also coincided with significant increase in ecosystem respiration, soil carbon and nitrogen, and with significantly lower soil pH and soil temperatures. The ecosystem respiration was high inside the gull colonies, similar to the highest fluxes measured in drained wetlands or agricultural fields in Iceland. The most important factor for vegetation succession and ecosystem function on Surtsey seems to be the amount of nitrogen, which was mainly brought in by the seagulls.

  4. Application of Spectroscopic Techniques (FT-IR, 13C NMR) to the analysis of humic substances in volcanic soils along an environmental gradient (Tenerife, Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Rodriguez Rodriguez, Antonio; María Armas Herrera, Cecilia; González Pérez, José Antonio; González-Vila, Francisco Javier; Arbelo Rodríguez, Carmen Dolores; Mora Hernández, Juan Luis; Polvillo Polo, Oliva

    2010-05-01

    Andosols and andic soils are considered as efficient C-sinks in terms of C sequestration. These soils are usually developed from volcanic materials, and are characterized by a predominance of short-range ordered minerals like allophanes, imogolite and other Fe and Al oxyhydroxides. Such materials occur commonly associated with organic compounds, thus generating highly stable organo-mineral complexes and leading to the accumulation of a high amount of organic carbon. Spectroscopic methods like FT-IR and 13C NMR are suitable for the analysis of the chemical structure of soil humic substances, and allow identifying distinct functional groups and protein, lipids, lignin, carbohydrate-derived fragments. In this work we study the structural features of four soils developed on Pleistocene basaltic lavae in Tenerife (Canary Island, Spain), distributed along an altitudinal climatic gradient. The soil sequence comprises soils with different degree of geochemical evolution and andic character, including a mineral ‘Hypersalic Solonchak' (Tabaibal de Rasca), a slightly vitric ‘Luvic Phaeozem' (Los Frailes), a degraded and shallow ‘Endoleptic, fulvic, silandic Andosol' (Siete Lomas), and a well-developed and deep ‘Fulvic, silandic, Andosol' (Ravelo). Samples of the raw soil and humic and fulvic acids isolated from the surface horizons were analyzed. The results show a low content of organic carbon in the mineral soil, the inherited humin predominating, and a very high content of humic and fulvic acids in Andosols. The FT-IR and 13C NMR spectra of the raw soil samples show a low resolution, related to interferences from mineral complexes signals, particularly in soils with lower organic carbon content. 13C NMR shows a predominance of O-alkyl carbon (derived of carbohydrates) in andic soils, whereas O-alkyl and aromatic fractions are most evident in the mineral soil. The humic acids spectra are characterized by a dominance of alkyl and aromatic fractions with a high degree

  5. Spatial variability in depth and landscape of heavy metal contents of volcanic soils of the National Cajas Park in the Azuay Andes (Ecuador)

    NASA Astrophysics Data System (ADS)

    Bech, Jaume; Roca, Núria; Boluda, Rafael; Gil, Carlos; Ramos-Miras, Joaquín; Rodríguez, Jose A.

    2015-04-01

    Although the soils in the Azuay Andes are thought to be generally non-contaminated, it is necessary to preserve them from anthropogenic pollution. This area supplies drinking water to Cuenca, the third city of Ecuador. At present, very little information is available on baseline metal concentrations in Latin American soils. Therefore, it is important to establish the baseline of elements in soils as reference values for evaluating potential changes in their concentrations and to be able to define their origins. The objectives of this study are: (1) to show morphological, physical and chemical characteristics of Andisols in the Azuay Andes (Ecuador); (2) to determine the concentrations of six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) and (3) to evaluate the relationship between metal concentration and soil properties. The study area is located in National Cajas Park in the Paramo area of the Andes at Azuay Province (Ecuador). The geological origin of the National Cajas Park dates back to the Quaternary age. This area is a U-shaped glaciated valley formed over a pre-existing volcanic basement which consists of rhyolite and andesite volcanic tuff. The moraines are covered by discontinuous patches of volcanic ash. The climate is characterized by rather high rainfall, between 1200 to 2000 mm per year, regularly distributed and generally of a low intensity with a yearly average constant temperature (7°C) with high diurnal amplitudes. The paramo is a high altitude neotropical grassland ecosystem, located between the continuous forest border (~3500 m) and the eternal snow line (~5000 m). Seven representative volcanic soil pedons of a toposequence were studied and sampled. All horizons were analysed for physical and chemical properties by standard and specific methods for volcanic soils. Total metal concentrations in soil horizons were determined by ICP-MS spectrometer. The background values were calculated using the 4σ-outlier test. This requires the elimination of

  6. Spatial and temporal variations of soil CO2 degassing rate at El Hierro volcanic system and relation to the 2011 submarine eruption

    NASA Astrophysics Data System (ADS)

    Melían, G.; Barrancos, J.; Padilla, G.; Dionis, S.; Rodríguez, F.; Nolasco, D.; Padrón, E.; Hernández, P. A.; Calvo, D.; Hernández, I.; Peréz, N. M.; Peraza, M. D.

    2012-04-01

    El Hierro Island (278 km2) is the youngest and the SW-most of the Canary Islands. On July 16, 2011, a seismic-volcanic crisis started with the occurrence of more than 11,900 seismic events. On October 10, 2011, the seismic activity changed behaviour and produced a harmonic tremor due to magma movement suggesting the initial stage of an eruption. The purpose of this study is to investigate the spatial and temporal variations of soil CO2 degassing rates at El Hierro volcanic system and its relation with the 2011 El Hierro volcanic unrest. Since 1998, diffuse CO2 emission has been investigated at El Hierro volcanic system in a yearly basis during the summer periods with approximately 600 observation sites. From 2004 to 2009, a diffuse CO2 emission rate decreasing trend from 1434 to 358 t•d-1 (equivalent to background values) was observed, and this tendency changed from 2009 to 2010 reaching a diffuse CO2 emission rate of 970 t•d-1. Because of this observed tendency change on the diffuse CO2 emission rate is possible to think that the preliminary stages of the 2011 volcanic unrest at El Hierro did start by the middle of 2010 with aseismic magma rising in the upper mantle beneath El Hierro. Since July 2011 and due to the start of the seismic-volcanic crisis at El Hierro, 16 diffuse CO2 emission surveys have been undertaken until January 2012. Diffuse CO2 emission measurements were performed by means of portable NDIR sensors according to the accumulation chamber method. Observed soil CO2 efflux values for all the 2011-12 surveys have ranged from negligible values to 398 g•m-2•d-1. The diffuse CO2 output released to atmosphere for the 2011-12 surveys was estimated between 138 and 2,143 t•d-1. On October 6, 2011, an increase tendency of diffuse CO2 emission rate from 380 to 990 t•d-1 was observed prior the occurrence of the first 4 magnitude type earthquake on October 8, 2011, and El Hierro submarine eruption on October 12, 2011. From October 15, 2011, an

  7. Natural Terrestrial Sequestration Potential of Highplains Prairie to Subalpine Forest and Mined-Lands Soils Derived from Weathering of Tertiary Volcanics

    NASA Astrophysics Data System (ADS)

    Yager, D. B.; Burchell, A.; Robinson, R.; Odell, S.; Dick, R. P.; Johnson, C. A.; Hidinger, J.; Rathke, D.

    2007-12-01

    There is now widespread agreement that, if the climate is to be stabilized, then net greenhouse gas emissions must be greatly reduced (IPCC, 2007). The need to reduce net CO2 emissions plus the possible economic and environmental ramifications of not addressing climate change have stimulated important atmospheric carbon mitigation actions, as well as, studies to understand and quantify potential carbon sinks. Soils represent a potentially large and environmentally significant natural carbon reservoir. Increasing the natural terrestrial sequestration potential (NTS) of soils is among the seven, "Sokolow CO2 stabilization wedges' or carbon management strategies needed to thwart doubling of atmospheric CO2. Additionally, high plains to subalpine temperate soils tend to be less susceptible to baseline C pool declines due to global warming than are warmer regions and are important ecosystems in which to quantify soil carbon storage capacity. To examine the potential of magnesium silicate-bearing soils to sequester additional carbon, we sampled 60 high plains prairie to subalpine forest soil horizons derived from weathering of Tertiary-age dacite-andesite- basalt compositions in Colorado, U.S.A.: the San Luis Valley, San Juan Volcanic Field, Grand Mesa, White River- Roan Plateau (Flat Tops), Rocky Mountain National Park, Front Range and propylitically-altered terrain in the western San Juan Volcanic field containing secondary magnesium silicates (chlorite-species). Data for C, N, O (total conc., isotopes), metals, major and trace elements, Hg, S, microbial enzymes (β-glucosidase, arylsulfatase, acid neutralizing capacity (ANC), and 14C radiocarbon dates are reported. Samples demonstrate variable but elevated C relative to average global soil C. In particular, the propylitically-altered rocks have a high instantaneous ANC in laboratory tests (> 20 kg/ton CaCO3 equivalent) and derivative forest soils containing low-temperature charcoal "burn" horizons have high total

  8. RHOBOT: Radiation hardened robotics

    SciTech Connect

    Bennett, P.C.; Posey, L.D.

    1997-10-01

    A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

  9. Precipitation hardening austenitic superalloys

    DOEpatents

    Korenko, Michael K.

    1985-01-01

    Precipitation hardening, austenitic type superalloys are described. These alloys contain 0.5 to 1.5 weight percent silicon in combination with about 0.05 to 0.5 weight percent of a post irradiation ductility enhancing agent selected from the group of hafnium, yttrium, lanthanum and scandium, alone or in combination with each other. In addition, when hafnium or yttrium are selected, reductions in irradiation induced swelling have been noted.

  10. Nuclear effects hardened shelters

    NASA Astrophysics Data System (ADS)

    Lindke, Paul

    1990-11-01

    The Houston Fearless 76 Government Projects Group has been actively engaged for more than twenty-five years as a sub-contractor and currently as a prime contractor in the design, manufacture, repair and logistics support of custom mobile ground stations and their equipment accommodations. Other associated products include environmental control units (ECU's), mobilizers for shelters and a variety of mobile power generation units (MPU's). Since 1984, Houston Fearless 76 has designed and manufactured four 8' x 8' x 22' nuclear hardened mobile shelters. These shelters were designed to contain electronic data processing/reduction equipment. One shelter is currently being operated by the Air Force as a Defense Intelligence Agency (DIA) approved and certified Special Corrpartmented Information Facility (SCIF). During the development and manufacturing process of the shelters, we received continual technical assistance and design concept evaluations from Science Applications International Corporation (SAIC) Operations Analysis and Logistics Engineering Division and the Nondestructive Inspection Lab at McClellan AFB. SAIC was originally employed by the Air Force to design the nuclear hardening specifications applied to these shelters. The specific levels of hardening to which the shelters were designed are classified and will not be mentioned during this presentation.

  11. Precipitation, strength and work hardening of age hardened aluminium alloys

    NASA Astrophysics Data System (ADS)

    Ryen, Ø.; Holmedal, B.; Marthinsen, K.; Furu, T.

    2015-08-01

    The strength and work hardening of age hardened AA6063 and AA6082 alloys have been investigated in terms of a detailed characterization of precipitate and dislocation structures obtained by TEM and SEM. Tensile and compression tests were performed at as quenched, peak aged and severely aged conditions. A strong work hardening in the as quenched condition was found, similar to AlMg alloys with twice as much alloying elements in solid solution. It was found that the initial work hardening rate and the critical failure strain are both smallest at the peak aged condition. During large deformations the needle-shaped precipitates are sheared uniformly by dislocations altering their <001> orientations, which indicates extensive cross slip. In the overaged condition the early initial work hardening is larger than at the peak aged condition, but followed by a weak linear work hardening, apparently directly entering stage IV at a low strain. Cracked, needle-shaped precipitates were seen at larger strains.

  12. Nature of organo-mineral particles across density fractions in a volcanic-ash soil: air-drying and sonication effect

    NASA Astrophysics Data System (ADS)

    Wagai, R.; Kajiura, M.; Shirato, Y.; Uchida, M.

    2011-12-01

    Interactions of plant- and microbially-derived organic matter with mineral phases exert significant controls on the stabilization of organic matter (OM) as well as other biogeochemical processes in soil. Density fractionation techniques have been successful in distinguishing soil organo-mineral particles of different degrees of microbial alteration, turnover rate of C, mineral associations. A major methodological difference among the density fractionation studies is the choice of sample pre-treatment. Presence or absence of sonication to disrupt and disperse soil particles and aggregates is a particularly important choice which could significantly alter the nature and distribution of organo-mineral particle and thus the resultant elemental concentration in each density fraction. Soil moisture condition (air-dry vs. field-moist) may also have strong impact especially for soils rich in Fe oxides/hydroxides and/or poorly-crystalline minerals that are prone for (possibly irreversible) aggregation. We thus tested these two effects on the concentration and distribution of C, N, and extractable phases of Fe and Al (by pyrophosphate and acid oxalate) across six density fractions (from <1.6 to >2.5 g/cm^3) using a surface-horizon of volcanic-ash soil which contained large amounts of poorly-crystalline minerals and organo-metal complexes. Compared to field-moist sample, air-drying had little effects on the elemental concentration or distribution across the fractions. In contrast, sonication on air-dried sample at each density cutoff during fractionation process caused significant changes. In addition to well-known increase in low-density material due to the liberation of plant detritus upon aggregate disruption, we found clear increase in C, N, and metals in 2.0-2.3 g/cm^3 fraction, which was largely compensated by the reduction in 1.8-2.0 g/cm^3 and, to a less extent, 2.3-2.5 g/cm^3 particles. Overall, sonication led to the redistribution of C and N by 15-20% and that of

  13. Practical aspects of systems hardening

    SciTech Connect

    Shepherd, W.J.

    1989-01-01

    Applications of hardening technology in a practical system require a balance between the factors governing affordability, producibility, and survivability of the finished design. Without careful consideration of the top-level system operating constraints, a design engineer may find himself with a survivable but overweight, unproductive, expensive design. This paper explores some lessons learned in applying hardening techniques to several laser communications programs and is intended as an introductory guide to novice designers faced with the task of hardening a space system.

  14. Industrial Hardening Demonstration.

    DTIC Science & Technology

    1980-09-01

    less severe conditions than thermal cracking (850’ - 950°F and 10 to 20 psi). Zeolitic or molecular sieve- base catalysts are used. Catalytic reforming...with Potential Industrial Hardening A-1 Participants B Post-Attack Petroleum Refining (and Production) B-1 from Crude Oil V List of Figures Number Page...the Key Worker Shelter 116 viii B-1 Proportions of the Products Obtained by Distillation B-2 of Six Crude Oils B-2 Generalized Flow Chart of the

  15. Catastrophic volcanism

    NASA Technical Reports Server (NTRS)

    Lipman, Peter W.

    1988-01-01

    Since primitive times, catastrophes due to volcanic activity have been vivid in the mind of man, who knew that his activities in many parts of the world were threatened by lava flows, mudflows, and ash falls. Within the present century, increasingly complex interactions between volcanism and the environment, on scales not previously experienced historically, have been detected or suspected from geologic observations. These include enormous hot pyroclastic flows associated with collapse at source calderas and fed by eruption columns that reached the stratosphere, relations between huge flood basalt eruptions at hotspots and the rifting of continents, devastating laterally-directed volcanic blasts and pyroclastic surges, great volcanic-generated tsunamis, climate modification from volcanic release of ash and sulfur aerosols into the upper atmosphere, modification of ocean circulation by volcanic constructs and attendent climatic implications, global pulsations in intensity of volcanic activity, and perhaps triggering of some intense terrestrial volcanism by planetary impacts. Complex feedback between volcanic activity and additional seemingly unrelated terrestrial processes likely remains unrecognized. Only recently has it become possible to begin to evaluate the degree to which such large-scale volcanic processes may have been important in triggering or modulating the tempo of faunal extinctions and other evolutionary events. In this overview, such processes are examined from the viewpoint of a field volcanologist, rather than as a previous participant in controversies concerning the interrelations between extinctions, impacts, and volcanism.

  16. Detection of an organic-non volatile compound in variable-contaminated volcanic soil samples via Time Domain Reflectometry (TDR) technique: Preliminary results

    NASA Astrophysics Data System (ADS)

    comegna, alessandro; coppola, antonio; dragonetti, giovanna; chaali, nesrine; sommella, angelo

    2014-05-01

    Hydrocarbons may be present in soils as non-aqueous phase liquids (NAPLs), which means that these organic compounds, exist as a separate and immiscible phase with respect to water and air commonly present in the soil. NAPLs, which can be accidentally introduced in the environment (for example by waste disposal sites, industrial spills, gasoline stations, etc), constitutes a serious geo-environmental problem, given the toxicity level and the high mobility. Time domain reflectometry (TDR) has became, over several decades, an important technique for water estimation in soils. In order to expand the potentiality of the TDR technique, the main objective of this study is to explore the capacity of dielectric response to detect the presence of NAPLs in volcanic soils. In laboratory, soil samples were oven dried at 105° C and passed through a 2 mm sieve. Known quantities of soil, water and NAPL (corn oil, a non-volatile and non-toxic organic compound) were mixed and repacked into plastic cylinders (16 cm high and 9.5 cm in diameter); in order to obtain forty different volumetric combinations of water and oil (i.e. θfg = θwater + θNAPL), with θNAPL varying from 0.05 to 0.40 by 0.05 cm3/cm3 increments. Data collected were employed to implement a multiphase mixing model which permitted conversion from a dielectric permittivity domain into a θf domain and vice versa. The results of this study show that, the TDR device is NAPL-sensitive, especially for θf values greater than 0.20. Further works will be built on this initial study, concentrating on improving the dielectric response-database, in order to: i) enhancing the model efficiency in terms of NAPL capability detention, and ii) validating the developed TDR interpretation tool with field results.

  17. The surface of Syrtis Major - Composition of the volcanic substrate and mixing with altered dust and soil

    NASA Astrophysics Data System (ADS)

    Mustard, J. F.; Erard, S.; Bibring, J.-P.; Head, J. W.; Hurtrez, S.; Langevin, Y.; Pieters, C. M.; Sotin, C. J.

    1993-02-01

    The study characterizes Syrtis Major, an old, low relief volcanic plateau near the equatorial regions of Mars, on the basis of ISM data in order to characterize the spectral properties of the surface, to identify the major mafic mineralogy of the volcanic materials, and to derive estimates of the chemistry of these minerals. The value and spatial distribution of four primary spectral variables (albedo, continuum slope, wavelength of the ferric-ferrous band minimum, and area of the ferric-ferrous absorption) are mapped and coregistered to Viking digital photomosaics. It is shown that although there is a high degree of overall spectral variability on the plateau, the key indicators of mafic mineralogy are relatively homogeneous.

  18. Devices and methods to measure H2 and CO2 concentrations in gases released from soils and low temperature fumaroles in volcanic areas

    NASA Astrophysics Data System (ADS)

    di Martino, R. M. R.; Camarda, M.; Gurrieri, S.; Valenza, M.

    2009-04-01

    Hydrogen solubility and diffusion have a great relevance to change the redox state of magmas, usually expressed by oxygen fugacity. This influences many chemical and physical properties, such as oxidation state of multivalent elements, kind and abundance of minerals and gas species. These processes change the phase ratios into the volcanic system and so the magma movement capability toward the earth surface and the eruptive dynamics. In past studies several authors (Carapezza et al., 1980; Sato et al., 1982; Sato and McGee, 1985; Wakita et al., 1980) proposed the application of the fuel cells in order to measure reducing capacity of volcanic gases. Their found some clear correlations between variation peaks and volcanic activity but a few reducing capacity changes showed no correlation with it. In this study we characterize a fuel cell device designed to measure hydrogen concentration in a gas mixture. We present test results obtained in laboratory and in field trip, carried out to verify the major interferences of others reducing gas species, commonly present in volcanic emissions, in the measurement carried out with a hydrogen fuel cell sensor. Tests were performed at controlled temperature ad pressure conditions and at air saturated pressure vapour in the cell cathode. A new device to measure simultaneously hydrogen (H2) and carbon dioxide (CO2) concentrations in soil and in low temperature fumaroles in volcanic areas was proposed. The H2-detector is a hydrogen fuel cell, whereas CO2 is measured using an I.R. spectrometer. To build a continuous monitoring station of volcanic activity both sensors were put in a case together with a data logger. Our device has 0.2 mV ppm-1 sensitivity, accuracy of ± 5 ppm and about 10 ppm resolution whit respect to the hydrogen concentration. These instrumental characteristics were obtained applying a 500 ohm resistor to the external circuit that represents the best compromise between sensitivity, resolution, instrumental

  19. Volcanic rocks

    USGS Publications Warehouse

    1986-01-01

    Volcanoes have contributed significantly to the formation of the surface of our planet. Volcanism produced the crust we live on and most of the air we breathe. Often the remnants of an eruption are as revealing as the eruption itself, for they tell us many things about the eruption. Included here are examples of several volcanic products and other magmatic features, with descriptions of how they were formed and what they tell us about volcanism.

  20. Volcanic Ash on Slopes of Karymsky

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A volcanic eruption can produce gases, lava, bombs of rock, volcanic ash, or any combination of these elements. Of the volcanic products that linger on the land, most of us think of hardened lava flows, but volcanic ash can also persist on the landscape. One example of that persistence appeared on Siberia's Kamchatka Peninsula in spring 2007. On March 25, 2007, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the area around the Karymsky Volcano. In this image, volcanic ash from earlier eruptions has settled onto the snowy landscape, leaving dark gray swaths. The ash stains are confined to the south of the volcano's summit, one large stain fanning out toward the southwest, and another toward the east. At first glance, the ash stain toward the east appears to form a semicircle north of the volcano and sweep back east. Only part of this dark shape, however, is actually volcanic ash. Near the coast, the darker color may result from thicker vegetation. Similar darker coloring appears to the south. Volcanic ash is not really ash at all, but tiny, jagged bits of rock and glass. These jagged particles pose serious health risks to humans and animals who might inhale them. Likewise, the ash poses hazards to animals eating plants that have been coated with ash. Because wind can carry volcanic ash thousands of kilometers, it poses a more far-reaching hazard than other volcanic ejecta. Substantial amounts of ash can even affect climate by blocking sunlight. Karymsky is a stratovolcano composed of alternating layers of solidified ash, hardened lava, and volcanic rocks. It is one of many active volcanoes on Russia's Kamchatka Peninsula, which is part of the 'Ring of Fire' around the Pacific Rim. NASA image created by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  1. Assessment of organic matter resistance to biodegradation in volcanic ash soils assisted by automated interpretation of infrared spectra from humic acid and whole soil samples by using partial least squares

    NASA Astrophysics Data System (ADS)

    Hernández, Zulimar; Pérez Trujillo, Juan Pedro; Hernández-Hernández, Sergio Alexander; Almendros, Gonzalo; Sanz, Jesús

    2014-05-01

    From a practical viewpoint, the most interesting possibilities of applying infrared (IR) spectroscopy to soil studies lie on processing IR spectra of whole soil (WS) samples [1] in order to forecast functional descriptors at high organizational levels of the soil system, such as soil C resilience. Currently, there is a discussion on whether the resistance to biodegradation of soil organic matter (SOM) depends on its molecular composition or on environmental interactions between SOM and mineral components, such could be the case with physical encapsulation of particulate SOM or organo-mineral derivatives, e.g., those formed with amorphous oxides [2]. A set of about 200 dependent variables from WS and isolated, ash free, humic acids (HA) [3] was obtained in 30 volcanic ash soils from Tenerife Island (Spain). Soil biogeochemical properties such as SOM, allophane (Alo + 1 /2 Feo), total mineralization coefficient (TMC) or aggregate stability were determined in WS. In addition, structural information on SOM was obtained from the isolated HA fractions by visible spectroscopy and analytical pyrolysis (Py-GC/MS). Aiming to explore the potential of partial least squares regression (PLS) in forecasting soil dependent variables, exclusively using the information extracted from WS and HA IR spectral profiles, data were processed by using ParLeS [4] and Unscrambler programs. Data pre-treatments should be carefully chosen: the most significant PLS models from IR spectra of HA were obtained after second derivative pre-treatment, which prevented effects of intrinsically broadband spectral profiles typical in macromolecular heterogeneous material such as HA. Conversely, when using IR spectra of WS, the best forecasting models were obtained using linear baseline correction and maximum normalization pre-treatment. With WS spectra, the most successful prediction models were obtained for SOM, magnetite, allophane, aggregate stability, clay and total aromatic compounds, whereas the PLS

  2. Using Uranium-series isotopes to understand processes of rapid soil formation in tropical volcanic settings: an example from Basse-Terre, French Guadeloupe

    NASA Astrophysics Data System (ADS)

    Ma, Lin

    2015-04-01

    Lin Ma1, Yvette Pereyra1, Peter B Sak2, Jerome Gaillardet3, Heather L Buss4 and Susan L Brantley5, (1) University of Texas at El Paso, El Paso, TX, United States, (2) Dickinson College, Carlisle, PA, United States, (3) Institute de Physique d Globe Paris, Paris, France, (4) University of Bristol, Bristol, United Kingdom, (5) Pennsylvania State University Main Campus, University Park, PA, United States Uranium-series isotopes fractionate during chemical weathering and their activity ratios can be used to determine timescales and rates of soil formation. Such soil formation rates provide important information to understand processes related to rapid soil formation in tropical volcanic settings, especially with respect to their fertility and erosion. Recent studies also highlighted the use of U-series isotopes to trace and quantify atmospheric inputs to surface soils. Such a process is particularly important in providing mineral nutrients to ecosystems in highly depleted soil systems such as the tropical soils. Here, we report U-series isotope compositions in thick soil profiles (>10 m) developed on andesitic pyroclastic flows in Basse-Terre Island of French Guadeloupe. Field observations have shown heterogeneity in color and texture in these thick profiles. However, major element chemistry and mineralogy show some general depth trends. The main minerals present throughout the soil profile are halloysite and gibbsite. Chemically immobile elements such as Al, Fe, and Ti show a depletion profile relative to Th while elements such as K, Mn, and Si show a partial depletion profile at depth. Mobile elements such as Ca, Mg, and Sr have undergone intensive weathering at depths, and an addition profile near the surface, most likely related to atmospheric inputs. (238U/232Th) activity ratios in one soil profile from the Brad David watershed in this study ranged from 0.374 to 1.696, while the (230Th/232Th) ratios ranged from 0.367 to 1.701. A decrease of (238U/232Th) in the

  3. System-Level Radiation Hardening

    NASA Technical Reports Server (NTRS)

    Ladbury, Ray

    2014-01-01

    Although system-level radiation hardening can enable the use of high-performance components and enhance the capabilities of a spacecraft, hardening techniques can be costly and can compromise the very performance designers sought from the high-performance components. Moreover, such techniques often result in a complicated design, especially if several complex commercial microcircuits are used, each posing its own hardening challenges. The latter risk is particularly acute for Commercial-Off-The-Shelf components since high-performance parts (e.g. double-data-rate synchronous dynamic random access memories - DDR SDRAMs) may require other high-performance commercial parts (e.g. processors) to support their operation. For these reasons, it is essential that system-level radiation hardening be a coordinated effort, from setting requirements through testing up to and including validation.

  4. Volcanic mesocyclones.

    PubMed

    Chakraborty, Pinaki; Gioia, Gustavo; Kieffer, Susan W

    2009-03-26

    A strong volcanic plume consists of a vertical column of hot gases and dust topped with a horizontal 'umbrella'. The column rises, buoyed by entrained and heated ambient air, reaches the neutral-buoyancy level, then spreads radially to form the umbrella. In classical models of strong volcanic plumes, the plume is assumed to remain always axisymmetric and non-rotating. Here we show that the updraught of the rising column induces a hydrodynamic effect not addressed to date-a 'volcanic mesocyclone'. This volcanic mesocyclone sets the entire plume rotating about its axis, as confirmed by an unprecedented analysis of satellite images from the 1991 eruption of Mount Pinatubo. Destabilized by the rotation, the umbrella loses axial symmetry and becomes lobate in plan view, in accord with satellite records of recent eruptions on Mounts Pinatubo, Manam, Reventador, Okmok, Chaiten and Ruang. The volcanic mesocyclone spawns waterspouts or dust devils, as seen in numerous eruptions, and groups the electric charges about the plume to form the 'lightning sheath' that was so prominent in the recent eruption of Mount Chaiten. The concept of a volcanic mesocyclone provides a unified explanation for a disparate set of poorly understood phenomena in strong volcanic plumes.

  5. Specific activities of natural rocks and soils at quaternary intraplate volcanism north of Sana’a, Yemen

    PubMed Central

    Harb, Shaban; El-Kamel, Abd El-Hadi; Abbady, Abd El-Bast; Saleh, Imran Issa; El-Mageed, Abdallah Ibrahim Abd

    2012-01-01

    The level of natural radioactivity in rocks and soil of 32 samples collected from locations at North Sana′a in Yemen was measured. Concentrations of radionuclides in rocks and soils samples were determined by gamma-ray spectrometer using high purity germanium (HPGe) detector with specially designed shield. The average radioactivity concentrations of 226Ra, 232Th, 40K were determined and expressed in Bq/kg. The results showed that these radionuclides were present in concentrations of 21.79 ± 3.1, 19.5 ± 2.6 and 399.3 ± 16 Bq/kg, respectively, for rocks. For soil, the corresponding values were 48.2 ± 4.4, 41.7 ± 4.5 and 939.1 ± 36 Bq/kg, respectively. Also, the radiological hazard of the natural radionuclide content, radium equivalent activity, total dose rates, external hazard index and gamma activity concentration index of the (rocks/soils) samples in the area under consideration were calculated. The dose rates at 1 m above the ground from terrestrial sources were 38.39 and 86.89 nGy/h for rocks and surface soil, respectively, which present no significant health hazards to humans. PMID:22363113

  6. Specific activities of natural rocks and soils at quaternary intraplate volcanism north of Sana'a, Yemen.

    PubMed

    Harb, Shaban; El-Kamel, Abd El-Hadi; Abbady, Abd El-Bast; Saleh, Imran Issa; El-Mageed, Abdallah Ibrahim Abd

    2012-01-01

    The level of natural radioactivity in rocks and soil of 32 samples collected from locations at North Sana'a in Yemen was measured. Concentrations of radionuclides in rocks and soils samples were determined by gamma-ray spectrometer using high purity germanium (HPGe) detector with specially designed shield. The average radioactivity concentrations of (226)Ra, (232)Th, (40)K were determined and expressed in Bq/kg. The results showed that these radionuclides were present in concentrations of 21.79 ± 3.1, 19.5 ± 2.6 and 399.3 ± 16 Bq/kg, respectively, for rocks. For soil, the corresponding values were 48.2 ± 4.4, 41.7 ± 4.5 and 939.1 ± 36 Bq/kg, respectively. Also, the radiological hazard of the natural radionuclide content, radium equivalent activity, total dose rates, external hazard index and gamma activity concentration index of the (rocks/soils) samples in the area under consideration were calculated. The dose rates at 1 m above the ground from terrestrial sources were 38.39 and 86.89 nGy/h for rocks and surface soil, respectively, which present no significant health hazards to humans.

  7. Planetary Volcanism

    NASA Technical Reports Server (NTRS)

    Antonenko, I.; Head, J. W.; Pieters, C. W.

    1998-01-01

    The final report consists of 10 journal articles concerning Planetary Volcanism. The articles discuss the following topics: (1) lunar stratigraphy; (2) cryptomare thickness measurements; (3) spherical harmonic spectra; (4) late stage activity of volcanoes on Venus; (5) stresses and calderas on Mars; (6) magma reservoir failure; (7) lunar mare basalt volcanism; (8) impact and volcanic glasses in the 79001/2 Core; (9) geology of the lunar regional dark mantle deposits; and (10) factors controlling the depths and sizes of magma reservoirs in Martian volcanoes.

  8. Case hardenability at high carbon levels

    SciTech Connect

    Walton, H.W.

    1995-02-01

    Loss of hardenability in the case was thought to be responsible for a lower than specified hardness found on a large carburized bushing. Pseudo Jominy testing on several high hardenability carburizing grades confirmed that hardenability fade was present at carbon levels above 0.65% and particularly for those steels containing molybdenum. Analysis of previous work provided a formula for calculating Jominy hardenability at various carbon levels. Again the results confirmed that the loss of hardenability was more severe in steels containing molybdenum.

  9. Cyclic aggradation and downcutting, fluvial response to volcanic activity, and calibration of soil-carbonate stages in the western Grand Canyon, Arizona

    USGS Publications Warehouse

    Lucchitta, Ivo; Curtis, Garniss H.; Davis, Marie E.; Davis, Sidney W.; Turrin, Brent

    2000-01-01

    In the western Grand Canyon, fluvial terraces and pediment surfaces, both associated with a Pleistocene basalt flow, document Quaternary aggradation and downcutting by the Colorado River, illuminate the river's response to overload and the end of overload, and allow calibration of soil-carbonate stages and determination of downcutting rates. Four downcutting-aggradation cycles are present. Each begins with erosion of older deposits to form a new river channel in which a characteristic suite of deposits is laid down. The current cycle (I) started ~700 yr B.P. The oldest (IV) includes the 603,000 ± 8000 to 524,000 ± 7000 yr Black Ledge basalt flow, emplaced when the river channel was ~30 m higher than it is now. The flow is overlain by basalt-cobble gravel and basalt sand. Soils reach the stage V level of carbonate development. Calibrated ages for soil stages are Stage V, ~525,000 yr; stage IV, <525,000 yr, ≥250,000 yr; stage III, <250,000 yr, ≥100,000 yr. The monolithologic basalt sand beds represent overloading by volcanic ash produced by an eruption 30-50 km upstream. The basalt-cobble beds signal breaching and rapid destruction of lava dams and erosion of flows. These deposits show that the Colorado River responds to overload by aggrading vigorously during the overload and then downcutting equally vigorously when the overload ends. The overall downcutting rate for the interval studied is 1.6 cm/1000 yr, much lower than rates upstream. The current downcutting rate, 11-14 m/1000 yr, likely is a response both to the end of late Pleistocene and early Holocene overload and to the reduction of sediment supply caused by Glen Canyon Dam.

  10. Cluster analysis of soil CO2 data from Mt. Etna (Italy) reveals volcanic influences on temporal and spatial patterns of degassing

    NASA Astrophysics Data System (ADS)

    Giammanco, Salvatore; Bonfanti, Pietro

    2009-03-01

    Soil CO2 concentration data were collected periodically from July 2001 to June 2005 from sampling site grids in two areas located on the lower flanks of Mt. Etna volcano (Paternò and Zafferana Etnea-Santa Venerina). Cluster analysis was performed on the acquired data in order to identify possible groups of sites where soil degassing could be fed by different sources. In both areas three clusters were recognised, whose average CO2 concentration values throughout the whole study period remained significantly different from one another. The clusters with the lowest CO2 concentrations showed time-averaged values ranging from 980 to 1,170 ppm vol, whereas those with intermediate CO2 concentrations showed time-averaged values ranging from 1,400 to 2,320 ppm vol, and those with the highest concentrations showed time-averaged values between 1,960 and 55,430 ppm vol. We attribute the lowest CO2 concentrations largely to a biogenic source of CO2. Conversely, the highest CO2 concentrations are attributed to a magmatic source, whereas the intermediate values are due to a variable mixing of the two sources described above. The spatial distribution of the CO2 values related to the magmatic source define a clear direction of anomalous degassing in the Zafferana Etnea-Santa Venerina area, which we attribute to the presence of a hidden fault, whereas in the Paternò area no such oriented anomalies were observed, probably because of the lower permeability of local soil. Time-series analysis shows that most of the variations observed in the soil CO2 data from both areas were related to changes in the volcanic activity of Mt. Etna. Seasonal influences were only observed in the time patterns of the clusters characterised by low CO2 concentrations, and no significant interdependence was found between soil CO2 concentrations and meteorological parameters. The largest observed temporal anomalies are interpreted as release of CO2 from magma batches that migrated from deeper to shallower

  11. Io volcanism

    SciTech Connect

    Carr, M.H.

    1985-01-01

    Io is the most volcanically active body in the Solar System. The Voyage spacecraft observed nine active eruption plumes in 1979, and detected numerous thermal anomalies. Loki the most active volcanic region has been emitting 1.5 x 10/sup 13/ W over the last few years. Many of the volcanic features have been interpreted as the result of sulfur volcanism because 1) the spectral reflectance of the surface resembles sulfur, 2) SO/sub 2/ has been positively identified, 3) the satellite leaves a trail of sulfur atoms in its wake; and 4) many of the hot spots have surfaces temperatures less than 400/sup 0/K, compatible with low-temperature melts. The evidence for sulfur has led to suggestions of sulfur lava flows hundreds of kilometers long, and sulfur lava lakes as large as Lake Erie. The observations are, however, equally compatible with basaltic volcanism. Modeling of the cooling of basaltic lava flows indicates that regions of basaltic volcanism on Io should have temperatures similar to those detected by the Voyager spacecraft. High eruption rates are required. High rates of fumarolic activity accompanying the eruptions and expulsion of volatiles by the plumes give the surface its sulfur-like spectral reflectance.

  12. Soil and river contamination patterns of chlordecone in a tropical volcanic catchment in the French West Indies (Guadeloupe).

    PubMed

    Crabit, A; Cattan, P; Colin, F; Voltz, M

    2016-05-01

    The aim of this study was to identify primary flow paths involved in the chlordecone (CLD) river contamination and quantify the CLD fluxes to assess CLD pollution levels and duration according to a typical catchment of the banana cropping area in the French Indies (Guadeloupe): the Pérou Catchment (12 km(2)) characterized by heavy rainfall (5686 mm year(-1)). Three sub-catchments (SC1, SC2 and SC3) were studied during the hydrological year 2009-2010: a pedological survey combined with a spatialized hydrochemical approach was conducted. The average soil concentration is higher in the Pérou Catchment (3400 μg kg(-1)) than in the entire banana cropping area in Guadeloupe (2100 μg kg(-1)). The results showed that CLD stocks in soils vary largely among soil types and farming systems: the weakest stocks are located upstream in SC1 (5 kg ha(-1)), where a majority of the area is non-cultivated; medium stocks are located in Nitisols downstream in SC3 (9 kg ha(-1)); and the greatest stocks are observed in SC2 on Andosols (12 kg ha(-1)) characterized by large farms. The annual water balance and the hydro-chemical analysis revealed that the three sub-catchments exhibited different behaviors. Pérou River contamination was high during low flows, which highlighted that contamination primarily originated from groundwater contributions. The results showed that only a small part of the catchment (SC2), contributing little to the water flow, comprises a major CLD contribution, which is in agreement with the highly contaminated andosol soils observed there. Another significant result considers that at least 50 years would be required to export the totality of the actual CLD soil stocks retained in the topsoil layer. The actual time for soil remediation will however be much longer considering (i) the necessary time for the chlordecone to percolate and be stored in the shallow aquifers and (ii) its travel time to reach the river.

  13. Sensitivity to volcanic field boundary

    NASA Astrophysics Data System (ADS)

    Runge, Melody; Bebbington, Mark; Cronin, Shane; Lindsay, Jan; Rashad Moufti, Mohammed

    2016-04-01

    Volcanic hazard analyses are desirable where there is potential for future volcanic activity to affect a proximal population. This is frequently the case for volcanic fields (regions of distributed volcanism) where low eruption rates, fertile soil, and attractive landscapes draw populations to live close by. Forecasting future activity in volcanic fields almost invariably uses spatial or spatio-temporal point processes with model selection and development based on exploratory analyses of previous eruption data. For identifiability reasons, spatio-temporal processes, and practically also spatial processes, the definition of a spatial region is required to which volcanism is confined. However, due to the complex and predominantly unknown sub-surface processes driving volcanic eruptions, definition of a region based solely on geological information is currently impossible. Thus, the current approach is to fit a shape to the known previous eruption sites. The class of boundary shape is an unavoidable subjective decision taken by the forecaster that is often overlooked during subsequent analysis of results. This study shows the substantial effect that this choice may have on even the simplest exploratory methods for hazard forecasting, illustrated using four commonly used exploratory statistical methods and two very different regions: the Auckland Volcanic Field, New Zealand, and Harrat Rahat, Kingdom of Saudi Arabia. For Harrat Rahat, sensitivity of results to boundary definition is substantial. For the Auckland Volcanic Field, the range of options resulted in similar shapes, nevertheless, some of the statistical tests still showed substantial variation in results. This work highlights the fact that when carrying out any hazard analysis on volcanic fields, it is vital to specify how the volcanic field boundary has been defined, assess the sensitivity of boundary choice, and to carry these assumptions and related uncertainties through to estimates of future activity and

  14. Effect of dissolved organic carbon on the transport and attachment behaviors of Cryptosporidium parvum oocysts and carboxylate-modified microspheres advected through temperate humic and tropical volcanic agricultural soil.

    PubMed

    Mohanram, Arvind; Ray, Chittaranjan; Metge, David W; Barber, Larry B; Ryan, Joseph N; Harvey, Ronald W

    2012-02-21

    Transport of Cryptosporidium parvum oocysts and microspheres in two disparate (a clay- and Fe-rich, volcanic and a temperate, humic) agricultural soils were studied in the presence and absence of 100 mg L(-1) of sodium dodecyl benzene sulfonate (SDBS), and Suwannee River Humic Acid (SRHA) at pH 5.0-6.0. Transport of carboxylate-modified, 1.8 μm microspheres in soil columns was highly sensitive to the nature of the dissolved organic carbon (DOC), whereas oocysts transport was more affected by soil mineralogy. SDBS increased transport of microspheres from 48% to 87% through the tropical soil and from 43% to 93% in temperate soil. In contrast, SRHA reduced transport of microspheres from 48% to 28% in tropical soil and from 43% to 16% in temperate soil. SDBS also increased oocysts transport through the temperate soil 5-fold, whereas no oocyst transport was detected in tropical soil. SRHA had only a nominal effect in increasing oocysts transport in tropical soil, but caused a 6-fold increase in transport through the temperate soil. Amendments of only 4 mg L(-1) SRHA and SDBS decreased oocyst hydrophobicity from 66% to 20% and from 66% to 5%, respectively. However, SDBS increased microsphere hydrophobicity from 16% to 33%. Soil fines, which includes clays, and SRHA, both caused the oocysts zeta potential (ζ) to become more negative, but caused the highly hydrophilic microspheres to become less negatively charged. The disparate behaviors of the two colloids in the presence of an ionic surfactant and natural organic matter suggest that microspheres may not be suitable surrogates for oocysts in certain types of soils. These results indicate that whether or not DOC inhibits or promotes transport of oocysts and microspheres in agricultural soils and by how much, depends not only on the surface characteristics of the colloid, but the nature of the DOC and the soil mineralogy.

  15. Alteration processes in volcanic soils and identification of exobiologically important weathering products on Mars using remote sensing

    NASA Astrophysics Data System (ADS)

    Bishop, Janice L.; Fröschl, Heinz; Mancinelli, Rocco L.

    1998-12-01

    Determining the mineralogy of the Martian surface material provides information about the past and present environments on Mars which are an integral aspect of whether or not Mars was suitable for the origin of life. Mineral identification on Mars will most likely be achieved through visible-infrared remote sensing in combination with other analyses on landed missions. Therefore, understanding the visible and infrared spectral properties of terrestrial samples formed via processes similar to those thought to have occurred on Mars is essential to this effort and will facilitate site selection for future exobiology missions to Mars. Visible to infrared reflectance spectra are presented here for the fine-grained fractions of altered tephra/lava from the Haleakala summit basin on Maui, the Tarawera volcanic complex on the northern island of New Zealand, and the Greek Santorini island group. These samples exhibit a range of chemical and mineralogical compositions, where the primary minerals typically include plagioclase, pyroxene, hematite, and magnetite. The kind and abundance of weathering products varied substantially for these three sites due, in part, to the climate and weathering environment. The moist environments at Santorini and Tarawera are more consistent with postulated past environments on Mars, while the dry climate at the top of Haleakala is more consistent with the current Martian environment. Weathering of these tephra is evaluated by assessing changes in the leachable and immobile elements, and through detection of phyllosilicates and iron oxide/oxyhydroxide minerals. Identifying regions on Mars where phyllosilicates and many kinds of iron oxides/oxyhydroxides are present would imply the presence of water during alteration of the surface material. Tephra samples altered in the vicinity of cinder cones and steam vents contain higher abundances of phyllosilicates, iron oxides, and sulfates and may be interesting sites for exobiology.

  16. Erosion Rates of Volcanic-ash Derived Soils in the Blue Mountains of Eastern Oregon, USA: A Comparison Across Sales in Space and Time.

    NASA Astrophysics Data System (ADS)

    Wondzell, S. M.; Clifton, C. F.; Harris, R. M.; Ritchie, J. C.

    2007-12-01

    We examined present day rates of erosion in the Blue Mountains of eastern Oregon to quantify background erosion rates to provide standards for assessing possible accelerated rates of erosion resulting from wild fire or from land-management activities such as prescribed fire. The Skookum Creek watersheds, where stream discharge and sediment yield have been recorded continuously since the watersheds were gauged in 1992, provided a watershed-scale estimate of erosion rates. We installed hillslope erosion plots on north- and south- facing slopes within the watersheds in 2002 and collected data for three years to estimate short-term, hillslope- scale erosion rates. We also collected soil samples and analyzed them for 137Cs to get a 40-yr time- integrated estimate of hillslope erosion rates. Our results showed large differences between whole-watershed sediment yields and hillslope erosion rates measured from plots, suggesting that episodic processes dominated sediment production and transport and therefore controlled watershed-scale sediment budgets. At the hillslope-scale, short-term erosion resulted primarily from digging by small mammals and trampling by elk. Visual observations at the plots suggested that annual down-slope sediment movement was usually less than one meter. There were no significant difference among slope positions, but erosion rates were significantly higher on south-facing aspects and positively correlated to the amount of bare ground. In contrast, the 137Cs data suggested that erosion rates differed with slope position. Higher erosion rates were measured in toe- and mid-slope positions, with little erosion occurring on upper slopes and ridge tops. We examine these results in light of the present-day pattern of surface soils resulting from redistribution of volcanic ash from upper- slope to lower-slope positions and the effects of disturbance, including wildfire and the preferential grazing of riparian and lower-slope positions by domestic livestock.

  17. Experiments and Spectral Studies of Martian Volcanic Rocks: Implications for the Origin of Pathfinder Rocks and Soils

    NASA Technical Reports Server (NTRS)

    Rutherford, Malcolm J.; Mustard, Jack; Weitz, Catherine

    2002-01-01

    The composition and spectral properties of the Mars Pathfinder rocks and soils together with the identification of basaltic and andesitic Mars terrains based on Thermal Emission Spectrometer (TES) data raised interesting questions regarding the nature and origin of Mars surface rocks. We have investigated the following questions: (1) are the Pathfinder rocks igneous and is it possible these rocks could have formed by known igneous processes, such as equilibrium or fractional crystallization, operating within SNC magmas known to exist on Mars? If it is possible, what P (depth) and PH2O conditions are required? (2) whether TES-based interpretations of plagioclase-rich basalt and andesitic terrains in the south and north regions of Mars respectively are unique. Are the surface compositions of these regions plagioclase-rich, possibly indicating the presence of old AI-rich crust of Mars, or are the spectra being affected by something like surface weathering processes that might determine the spectral pyroxene to plagioclase ratio?

  18. HARDENING FROG POINTS BY EXPLOSIVE ENERGY,

    DTIC Science & Technology

    Experiments were made to determine the most efficient method of strain hardening railroad frog points in order to increase their fatigue resistance...Mechanical strain hardening with rolls 40 mm in diameter under a load of 8 tons produced in standard frogs cast from G13L high-manganese steel (AISI...Hadfield steel) a work-hardened surface layer 3-5 mm thick with a hardness of 340 HB. In other experiments, the frogs were hardened by exploding a

  19. Precipitation hardening in aluminum alloy 6022

    SciTech Connect

    Miao, W.F.; Laughlin, D.E.

    1999-03-05

    Although the precipitation process in Al-Mg-Si alloys has been extensively studied, the understanding of the hardening process is still incomplete, since any change in composition, processing and aging practices, etc., could affect the precipitation hardening behavior. In this paper, hardness measurements, differential scanning calorimetry and transmission electron microscopy have been utilized to study the precipitation hardening behavior in aluminum alloy 6022.

  20. Soil CO2 degassing on Mt Etna (Sicily) during the period 1989 1993: discrimination between climatic and volcanic influences

    NASA Astrophysics Data System (ADS)

    Giammanco, Salvatore; Gurrieri, Sergio; Valenza, Mariano

    1995-03-01

    Wide variations were measured in the diffuse CO2 flux through the soils in three selected areas of Mt Etna between August 1989 and March 1993. Degassing of CO2 from the area of Zafferana Etnea-S. Venerina, on the eastern slope of the volcano, has been determined to be more strongly influenced by meteorological parameters than the other areas. The seasonal component found in the data from this area has been excluded using a filtering algorithm based on the best fitting equation calculated from the correlation between CO2 flux values and those of air temperature. The filtered data appear to have variations temporally coincident with those from the other areas, thus suggesting a common and probably deep source of gas. The highest fluxes measured in the two most peripheral areas may correlate well with other geophysical and volcanological anomalous signals that preceded the strong eruption of 1991 1993 and that were interpreted as deep pressure increases. Anomalous decreases in CO2 fluxes accompanied the onset and the evolution of that eruption and have been interpreted as a sign of upward migration of the gas source. The variations of CO2 flux at the 1989 SE fracture have also given interesting information on the timing of the magmatic intrusion that has then fed the 1991 1993 eruption.

  1. Surface Fatigue Resistance with Induction Hardening

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis; Turza, Alan; Chapman, Mike

    1996-01-01

    Induction hardening has been used for some years to harden the surface and improve the strength and service life of gears and other components. Many applications that employ induction hardening require a relatively long time to finish the hardening process and controlling the hardness of the surface layer and its depth often was a problem. Other surface hardening methods, ie., carbonizing, take a very long time and tend to cause deformations of the toothing, whose elimination requires supplementary finishing work. In double-frequency induction hardening, one uses a low frequency for the preheating of the toothed wheel and a much higher frequency for the purpose of rapidly heating the surface by way of surface hardening.

  2. Volcanic gas

    USGS Publications Warehouse

    McGee, Kenneth A.; Gerlach, Terrance M.

    1995-01-01

    In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.

  3. Volcanic Seismology

    NASA Astrophysics Data System (ADS)

    McNutt, Stephen R.

    2005-01-01

    Recent developments in volcanic seismology include new techniques to improve earthquake locations that have changed clouds of earthquakes to lines (faults) for high-frequency events and small volumes for low-frequency (LF) events. Spatial mapping of the b-value shows regions of normal b and high b anomalies at depths of 3-4 and 7-10 km. Increases in b precede some eruptions. LF events and very-long-period (VLP) events have been recorded at many volcanoes, and models are becoming increasingly sophisticated. Deep long-period (LP) events are fairly common, but may represent several processes. Acoustic sensors have greatly improved the study of volcanic explosions. Volcanic tremor is stronger for fissure eruptions, phreatic eruptions, and higher gas contents. Path and site effects can be extreme at volcanoes. Seismicity at volcanoes is triggered by large earthquakes, although mechanisms are still uncertain. A number of volcanoes have significant deformation with very little seismicity. Tomography has benefited from improved techniques and better instrumental arrays.

  4. Scintillation-Hardened GPS Receiver

    NASA Technical Reports Server (NTRS)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  5. Volcanic Catastrophes

    NASA Astrophysics Data System (ADS)

    Eichelberger, J. C.

    2003-12-01

    The big news from 20th century geophysics may not be plate tectonics but rather the surprise return of catastrophism, following its apparent 19th century defeat to uniformitarianism. Divine miracles and plagues had yielded to the logic of integrating observations of everyday change over time. Yet the brilliant interpretation of the Cretaceous-Tertiary Boundary iridium anomaly introduced an empirically based catastrophism. Undoubtedly, decades of contemplating our own nuclear self-destruction played a role in this. Concepts of nuclear winter, volcanic winter, and meteor impact winter are closely allied. And once the veil of threat of all-out nuclear exchange began to lift, we could begin to imagine slower routes to destruction as "global change". As a way to end our world, fire is a good one. Three-dimensional magma chambers do not have as severe a magnitude limitation as essentially two-dimensional faults. Thus, while we have experienced earthquakes that are as big as they get, we have not experienced volcanic eruptions nearly as great as those preserved in the geologic record. The range extends to events almost three orders of magnitude greater than any eruptions of the 20th century. Such a calamity now would at the very least bring society to a temporary halt globally, and cause death and destruction on a continental scale. At maximum, there is the possibility of hindering photosynthesis and threatening life more generally. It has even been speculated that the relative genetic homogeneity of humankind derives from an evolutionary "bottleneck" from near-extinction in a volcanic cataclysm. This is somewhat more palatable to contemplate than a return to a form of Original Sin, in which we arrived at homogeneity by a sort of "ethnic cleansing". Lacking a written record of truly great eruptions, our sense of human impact must necessarily be aided by archeological and anthropological investigations. For example, there is much to be learned about the influence of

  6. Volcanic features of Io

    USGS Publications Warehouse

    Carr, M.H.; Masursky, H.; Strom, R.G.; Terrile, R.J.

    1979-01-01

    Volcanic activity is apparently higher on Io than on any other body in the Solar System. Its volcanic landforms can be compared with features on Earth to indicate the type of volcanism present on Io. ?? 1979 Nature Publishing Group.

  7. DISPERSION HARDENING OF URANIUM METAL

    DOEpatents

    Arbiter, W.

    1963-01-15

    A method of hardening U metal involves the forming of a fine dispersion of UO/sub 2/. This method consists of first hydriding the U to form a finely divided powder and then exposing the powder to a very dilute O gas in an inert atmosphere under such pressure and temperature conditions as to cause a thin oxide film to coat each particle of the U hydride, The oxide skin prevents agglomeration of the particles as the remaining H is removed, thus preserving the small particle size. The oxide skin coatings remain as an oxide dispersion. The resulting product may be workhardened to improve its physical characteristics. (AEC)

  8. Energy-Efficient Thermomagnetic and Induction Hardening

    SciTech Connect

    2009-02-01

    This factsheet describes a research project that will develop and test a hybrid thermomagnetic and induction hardening technology to replace conventional heat treatment processes in forging applications.

  9. COSMIC-RAY HELIUM HARDENING

    SciTech Connect

    Ohira, Yutaka; Ioka, Kunihito

    2011-03-01

    Recent observations by the CREAM and ATIC-2 experiments suggest that (1) the spectrum of cosmic-ray (CR) helium is harder than that of CR protons below the knee energy, 10{sup 15}eV, and (2) all CR spectra become hard at {approx}>10{sup 11}eV nucleon{sup -1}. We propose a new idea, that higher energy CRs are generated in a more helium-rich region, to explain the hardening without introducing different sources for CR helium. The helium-to-proton ratio at {approx}100 TeV exceeds the Big Bang abundance Y = 0.25 by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in a chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium if CRs escape from the supernova remnant shock in an energy-dependent way. We provide a simple analytical spectrum that also fits well the hardening due to the decreasing Mach number in the hot superbubble with {approx}10{sup 6} K. Our model predicts hard and concave spectra for heavier CR elements.

  10. Improved hardening theory for cyclic plasticity.

    NASA Technical Reports Server (NTRS)

    Vos, R. G.; Armstrong, W. H.

    1973-01-01

    A temperature-dependent version of a combined hardening theory, including isotropic and kinematic hardening, is presented within the framework of recent plasticity formulations. This theory has been found to be especially useful in finite-element analysis of aerospace vehicle engines under conditions of large plastic strain and low-cycle fatigue.

  11. Volcanic hazard management in dispersed volcanism areas

    NASA Astrophysics Data System (ADS)

    Marrero, Jose Manuel; Garcia, Alicia; Ortiz, Ramon

    2014-05-01

    Traditional volcanic hazard methodologies were developed mainly to deal with the big stratovolcanoes. In such type of volcanoes, the hazard map is an important tool for decision-makers not only during a volcanic crisis but also for territorial planning. According to the past and recent eruptions of a volcano, all possible volcanic hazards are modelled and included in the hazard map. Combining the hazard map with the Event Tree the impact area can be zoned and defining the likely eruptive scenarios that will be used during a real volcanic crisis. But in areas of disperse volcanism is very complex to apply the same volcanic hazard methodologies. The event tree do not take into account unknown vents, because the spatial concepts included in it are only related with the distance reached by volcanic hazards. The volcanic hazard simulation is also difficult because the vent scatter modifies the results. The volcanic susceptibility try to solve this problem, calculating the most likely areas to have an eruption, but the differences between low and large values obtained are often very small. In these conditions the traditional hazard map effectiveness could be questioned, making necessary a change in the concept of hazard map. Instead to delimit the potential impact areas, the hazard map should show the expected behaviour of the volcanic activity and how the differences in the landscape and internal geo-structures could condition such behaviour. This approach has been carried out in La Palma (Canary Islands), combining the concept of long-term hazard map with the short-term volcanic scenario to show the expected volcanic activity behaviour. The objective is the decision-makers understand how a volcanic crisis could be and what kind of mitigation measurement and strategy could be used.

  12. Method of Hardening Glass-Reinforced Plastics,

    DTIC Science & Technology

    1988-02-09

    373 NETHOD OF HARDENING GLASS -REINFORCED PLASTICS (U) 1/i FOREIGN TECHNOLOGY DIV idRIGHT-PATTERSON NFS ON V F DOLGIKH ET AL 89 FEB 88 FTD-ID(RS)T-M49...FTD-ID(RS)T-0049-88 9 February 1988 MICROFICHE NR: FTD-tES-C-00219 METHOD OF HARDENING GLASS -REINFORCED PLASTICS By: V.F. Dolgikh, S.L. Roginskiy, et...translation were extracted from the best quality copy available. If 1 11i METHOD OF HARDENING GLASS -REINFORCED PLASTICS V. F. Dolgikh, S. L. Roginskiy, E. L

  13. Cyclic hardening mechanisms in Nimonic 80A

    NASA Technical Reports Server (NTRS)

    Lerch, B. A.; Gerold, V.

    1987-01-01

    A nickel base superalloy was fatigued under constant plastic strain range control. The hardening response was investigated as a function of plastic strain range and particle size of the gamma prime phase. Hardening was found to be a function of the slip band spacing. Numerous measurements of the slip band spacing and other statistical data on the slip band structures were obtained. Interactions between intersecting slip systems were shown to influence hardening. A Petch-Hall model was found to describe best this relationship between the response stress and the slip band spacing.

  14. Fatigue hardening in niobium single crystals.

    NASA Technical Reports Server (NTRS)

    Doner, M.; Diprimio, J. C.; Salkovitz, E. I.

    1973-01-01

    Nb single crystals of various orientations were cyclically deformed in tension-compression under strain control. At low strain amplitudes all crystals oriented for single slip and some oriented for multiple slip showed a two stage hardening. When present, the first stage was characterized with almost no cyclic work hardening. The rate of hardening in the second stage increased with strain amplitude and the amount of secondary slip. In crystals oriented for single slip kink bands developed on their side faces during rapid hardening stage which resulted in considerable amount of asterism in Laue spots. A cyclic stress-strain curve independent of prior history was found to exist which was also independent of crystal orientation. Furthermore, this curve differed only slightly from that of polycrystalline Nb obtained from data in literature.

  15. Extraordinary strain hardening by gradient structure.

    PubMed

    Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T

    2014-05-20

    Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures.

  16. Alloy solution hardening with solute pairs

    DOEpatents

    Mitchell, John W.

    1976-08-24

    Solution hardened alloys are formed by using at least two solutes which form associated solute pairs in the solvent metal lattice. Copper containing equal atomic percentages of aluminum and palladium is an example.

  17. Process for hardening the surface of polymers

    DOEpatents

    Mansur, L.K.; Lee, E.H.

    1992-07-14

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance. 1 figure.

  18. Process for hardening the surface of polymers

    DOEpatents

    Mansur, Louis K.; Lee, Eal H.

    1992-01-01

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance.

  19. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  20. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  1. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  2. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  3. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  4. [Beam hardening correction method for X-ray computed tomography based on subsection beam hardening curves].

    PubMed

    Huang, Kui-dong; Zhang, Ding-hua

    2009-09-01

    After researching the forming principle of X-ray beam hardening and analyzing the usual methods of beam hardening correction, a beam hardening correction model was established, in which the independent variable was the projection gray, and so the computing difficulties in beam hardening correction can be reduced. By considering the advantage and disadvantage of fitting beam hardening curve to polynomial, a new expression method of the subsection beam hardening curves based on polynomial was proposed. In the method, the beam hardening data were fitted firstly to a polynomial curve which traverses the coordinate origin, then whether the got polynomial curve surged in the fore-part or back-part of the fitting range was judged based on the polynomial curvature change. If the polynomial fitting curve surged, the power function curve was applied to replace the surging parts of the polynomial curve, and the C1 continuity was ensured at the joints of the segment curves. The experimental results of computed tomography (CT) simulation show that the method is well stable in the beam hardening correction for the ideal CT images and CT images with added noises, and can mostly remove the beam hardening artifact at the same time.

  5. Decline in Radiation Hardened Microcircuit Infrastructure

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.

    2015-01-01

    Two areas of radiation hardened microcircuit infrastructure will be discussed: 1) The availability and performance of radiation hardened microcircuits, and, and 2) The access to radiation test facilities primarily for proton single event effects (SEE) testing. Other areas not discussed, but are a concern include: The challenge for maintaining radiation effects tool access for assurance purposes, and, the access to radiation test facilities primarily for heavy ion single event effects (SEE) testing. Status and implications will be discussed for each area.

  6. Geochemical evidence for African dust and volcanic ash inputs to terra rossa soils on carbonate reef terraces, northern Jamaica, West Indies

    USGS Publications Warehouse

    Muhs, D.R.; Budahn, J.R.

    2009-01-01

    The origin of red or reddish-brown, clay-rich, "terra rossa" soils on limestone has been debated for decades. A traditional qualitative explanation for their formation has been the accumulation of insoluble residues as the limestone is progressively dissolved over time. However, this mode of formation often requires unrealistic or impossible amounts of carbonate dissolution. Therefore, where this mechanism is not viable and where local fluvial or colluvial inputs can be ruled out, an external source or sources must be involved in soil formation. On the north coast of the Caribbean island of Jamaica, we studied a sequence of terra rossa soils developed on emergent limestones thought to be of Quaternary age. The soils become progressively thicker, redder, more Fe- and Al-rich and Si-poor with elevation. Furthermore, although kaolinite is found in all the soils, the highest and oldest soils also contain boehmite. Major and trace element geochemistry shows that the host limestones and local igneous rocks are not likely source materials for the soils. Other trace elements, including the rare earth elements (REE), show that tephra from Central American volcanoes is not a likely source either. However, trace element geochemistry shows that airborne dust from Africa plus tephra from the Lesser Antilles island arc are possible source materials for the clay-rich soils. A third, as yet unidentified, source may also contribute to the soils. We hypothesize that older, more chemically mature Jamaican bauxites may have had a similar origin. The results add to the growing body of evidence of the importance of multiple parent materials, including far-traveled dust, to soil genesis.

  7. Properties and Commercial Application of Manual Plasma Hardening

    NASA Astrophysics Data System (ADS)

    Korotkov, V. A.

    2016-11-01

    A new method and a device for plasma hardening of various parts are considered. Installation of the new device does not require too much investment (the active mechanical productions are appropriate for its accommodation) and special choice of personnel (welders train to use it without difficulty). Plasma hardening does not deform and worsen the smoothness of the surface, which makes it possible to employ many hardened parts without finishing mechanical treatment required after bulk or induction hardening. The hardened layer (about 1 mm) produced by plasma hardening exhibits better wear resistance than after bulk hardening with tempering, which prolongs the service life of the parts.

  8. The secondary hardening phenomenon in strain-hardened MP35N alloy

    SciTech Connect

    Asgari, S.; El-Danaf, E.; Shaji, E.; Kalidindi, S.R.; Doherty, R.D.

    1998-10-09

    Mechanical testing and microscopy techniques were used to investigate the influence of aging on the structure and strengthening of MP35N alloy. It was confirmed that aging the deformed material at 600 C for 4 h provided additional strengthening, here referred to as secondary hardening, in addition to the primary strain hardening. The secondary hardening phenomenon was shown to be distinctly different from typical age hardening processes in that it only occurred in material deformed beyond a certain cold work level. At moderate strains, aging caused a shift in the entire stress-strain curve of the annealed material to higher stresses while at high strains, it produced shear localization and limited work softening. The secondary hardening increment was also found to be grain size dependent. The magnitude of the secondary hardening appeared to be controlled by the flow stress in the strain hardened material. A model is proposed to explain the observations and is supported by direct experimental evidence. The model is based on formation of h.c.p. nuclei through the Suzuki mechanism, that is segregation of solute atoms to stacking faults, on aging the strain hardened material. The h.c.p. precipitates appear to thicken only in the presence of high dislocation density produced by prior cold work.

  9. Detection of the pedogenic magnetic fraction in volcanic soils developed on basalts using frequency-dependent magnetic susceptibility: comparison of two instruments

    NASA Astrophysics Data System (ADS)

    Grison, Hana; Petrovsky, Eduard; Kapicka, Ales; Hanzlikova, Hana

    2017-01-01

    SUMMARYIn studies of the magnetic properties of <span class="hlt">soils</span>, the frequency-dependent magnetic susceptibility percentage (χFD%) is often used for the identification of ultrafine magnetically superparamagnetic/stable single-domain (SP/SSD) particles. This parameter is commonly used as an indicator for increased pedogenesis. In strongly magnetic <span class="hlt">soils</span>, the SP/SSD magnetic signal (mostly bio-pedogenic) may be masked by lithological signals; making pedogenesis hard to detect. In this study we compare results for the detection of ultrafine SP/SSD magnetic particles in andic <span class="hlt">soils</span> using two instruments: a Bartington MS2B dual-frequency meter and an AGICO Kappabridge MFK1-FA. In particular, the study focuses on the effect of pedogenesis by investigating the relationship between specific <span class="hlt">soil</span> magnetic and chemical properties (<span class="hlt">soil</span> organic carbon and pHH2O). The values of χFD% obtained with the MS2B varied from 2.4 to 5.9%, and mass-specific magnetic susceptibility (χLF) from 283 to 1688 × 10-8 m3 kg-1, while values of χFD% and χLF obtained with the MFK1-FA varied from 2.7 to 8.2% and from 299 to 1859 × 10-8 m3 kg-1, respectively. Our results suggest that the detection of the SP/SSD magnetic fraction can be accomplished by comparing relative trends of χFD% along the <span class="hlt">soil</span> profile. Moreover, the discrimination between bio-pedogenic and lithogenic magnetic contributions in the SP/SSD fraction is possible by comparing the χFD% and χLF data determined in the fine earth (<2 mm) and the coarse fraction (4-10 mm) samples down the <span class="hlt">soil</span> profile.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6250616','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6250616"><span>California's potential <span class="hlt">volcanic</span> hazards</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jorgenson, P. )</p> <p>1989-01-01</p> <p>Although <span class="hlt">volcanic</span> eruptions have occurred infrequently in California during the last few thousand years, the potential danger to life and property from volcanoes in the state is great enough to be of concern, according to a recent U.S. Geological Survey (USGS) publication. The 17-page bulletin, Potential Hazards from Future <span class="hlt">Volcanic</span> Eruptions in California, gives a brief history of <span class="hlt">volcanic</span> activity in California during the past 100,000 years, descriptions of the types of volcanoes in the state, the types of potentially hazardous <span class="hlt">volcanic</span> events that could occur, and hazard-zonation maps and tables depicting six areas of the state where <span class="hlt">volcanic</span> eruptions might occur. The six areas and brief descriptions of their past <span class="hlt">volcanic</span> history and potential for future <span class="hlt">volcanic</span> hazards are briefly summarized here.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SenIm..18....5R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SenIm..18....5R"><span>On Analytical Solutions to Beam-<span class="hlt">Hardening</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rigaud, G.</p> <p>2017-01-01</p> <p>When polychromatic X-rays propagate through a material, for instance in computerized tomography (CT), low energy photons are more attenuated resulting in a "harder" beam. The beam-<span class="hlt">hardening</span> phenomenon breaks the monochromatic radiation model based on the Radon transform giving rise to artifacts in CT reconstructions to the detriment of visual inspection and automated segmentation algorithms. We propose first a simplified analytic representation for the beam-<span class="hlt">hardening</span>. Besides providing a general understanding of the phenomenon, this model proposes to invert the beam-<span class="hlt">hardening</span> effect for homogeneous objects leading to classical monochromatic data. For heterogeneous objects, no analytical reconstruction of the density can be derived without more prior information. However, the beam-<span class="hlt">hardening</span> is shown to be a smooth operation on the data and thus to preserve the encoding of the singularities of the attenuation map within the data. A microlocal analysis encourages the use of contour extraction methods to solve partially the beam-<span class="hlt">hardening</span> effect even for heterogeneous objects. The application of both methods, exact analytical solution for homogeneous objects and feature extraction for heterogeneous ones, on real data demonstrates their relevancy and efficiency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880036810&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHardening','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880036810&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHardening"><span>Phenomenological modeling of <span class="hlt">hardening</span> and thermal recovery in metals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chan, K. S.; Lindholm, U. S.; Bodner, S. R.</p> <p>1988-01-01</p> <p>Modeling of <span class="hlt">hardening</span> and thermal recovery in metals is considered within the context of unified elastic-viscoplastic theories. Specifically, the choices of internal variables and <span class="hlt">hardening</span> measures, and the resulting <span class="hlt">hardening</span> response obtained by incorporating saturation-type evolution equations into two general forms of the flow law are examined. Based on the analytical considerations, a procedure for delineating directional and isotropic <span class="hlt">hardening</span> from uniaxial <span class="hlt">hardening</span> data has been developed for the Bodner-Partom model and applied to a nickel-base superalloy, B1900 + Hf. Predictions based on the directional <span class="hlt">hardening</span> properties deduced from the monotonic loading data are shown to be in good agreement with results of cyclic tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1027171','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1027171"><span>Modeling of Irradiation <span class="hlt">Hardening</span> of Polycrystalline Materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Li, Dongsheng; Zbib, Hussein M.; Garmestani, Hamid; Sun, Xin; Khaleel, Mohammad A.</p> <p>2011-09-14</p> <p>High energy particle irradiation of structural polycrystalline materials usually produces irradiation <span class="hlt">hardening</span> and embrittlement. The development of predict capability for the influence of irradiation on mechanical behavior is very important in materials design for next generation reactors. In this work a multiscale approach was implemented to predict irradiation <span class="hlt">hardening</span> of body centered cubic (bcc) alpha-iron. The effect of defect density, texture and grain boundary was investigated. In the microscale, dislocation dynamics models were used to predict the critical resolved shear stress from the evolution of local dislocation and defects. In the macroscale, a viscoplastic self-consistent model was applied to predict the irradiation <span class="hlt">hardening</span> in samples with changes in texture and grain boundary. This multiscale modeling can guide performance evaluation of structural materials used in next generation nuclear reactors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20726130','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20726130"><span>An Anisotropic <span class="hlt">Hardening</span> Model for Springback Prediction</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zeng, Danielle; Xia, Z. Cedric</p> <p>2005-08-05</p> <p>As more Advanced High-Strength Steels (AHSS) are heavily used for automotive body structures and closures panels, accurate springback prediction for these components becomes more challenging because of their rapid <span class="hlt">hardening</span> characteristics and ability to sustain even higher stresses. In this paper, a modified Mroz <span class="hlt">hardening</span> model is proposed to capture realistic Bauschinger effect at reverse loading, such as when material passes through die radii or drawbead during sheet metal forming process. This model accounts for material anisotropic yield surface and nonlinear isotropic/kinematic <span class="hlt">hardening</span> behavior. Material tension/compression test data are used to accurately represent Bauschinger effect. The effectiveness of the model is demonstrated by comparison of numerical and experimental springback results for a DP600 straight U-channel test.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2162R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2162R"><span>The geothermal system of Caviahue-Copahue <span class="hlt">Volcanic</span> Complex (Chile-Argentina): New insights from self-potential, <span class="hlt">soil</span> CO2 degassing, temperature measurements and helium isotopes, with structural and fluid circulation implications.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roulleau, Emilie; Bravo, Francisco; Barde-Cabusson, Stephanie; Pizarro, Marcela; Muños, Carlos; Sanchez, Juan; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; de Cal, Federico; Esteban, Carlos</p> <p>2016-04-01</p> <p>Geothermal systems represent natural heat transfer engines in a confined volume of rock which are strongly influenced by the regional volcano-tectonic setting controlling the formation of shallow magmatic reservoirs, and by the local faults/fracture network, that permits the development of hydrothermal circulation cells and promote the vertical migration of fluids and heat. In the Southern <span class="hlt">Volcanic</span> Zone of Chile-Argentina, geothermal resources occur in close spatial relationship with active <span class="hlt">volcanism</span> along the Cordillera which is primarily controlled by the 1000 km long, NNE Liquiñe-Ofqui Fault Zone (LOFZ), an intra-arc dextral strike-slip fault system, associated with second-order intra-arc anisotropy of overall NE-SW (extensional) and NW-SE orientation (compressional). However there is still a lack of information on how fault network (NE and WNW strinking faults) and lithology control the fluid circulation. In this study, we propose new data of dense self-potential (SP), <span class="hlt">soil</span> CO2 emanation and temperature (T) measurements within the geothermal area from Caviahue-Copahue <span class="hlt">Volcanic</span> Complex (CCVC), coupled with helium isotopes ratios measured in fumaroles and thermal springs. We observe that inside the geothermal system the NE-striking faults, characterized by a combination of SP-CO2 and T maxima with high 3He/4He ratios (7.86Ra), promote the formation of high vertical permeability pathways for fluid circulation. Whereas, the WNW-striking faults represent low permeability pathways for hydrothermal fluids ascent associated with moderate 3He/4He ratios (5.34Ra), promoting the infiltration of meteoric water at shallow depth. These active zones are interspersed by SP-CO2- T minima, which represent self-sealed zones (e.g. impermeable altered rocks) at depth, creating a barrier inhibiting fluids rise. The NE-striking faults seem to be associated with the upflow zones of the geothermal system, where the boiling process produces a high vapor-dominated zone close to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070037453','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070037453"><span>Radiation <span class="hlt">Hardened</span> Electronics for Space Environments (RHESE)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keys, Andrew S.; Adams, James H.; Frazier, Donald O.; Patrick, Marshall C.; Watson, Michael D.; Johnson, Michael A.; Cressler, John D.; Kolawa, Elizabeth A.</p> <p>2007-01-01</p> <p>Radiation Environmental Modeling is crucial to proper predictive modeling and electronic response to the radiation environment. When compared to on-orbit data, CREME96 has been shown to be inaccurate in predicting the radiation environment. The NEDD bases much of its radiation environment data on CREME96 output. Close coordination and partnership with DoD radiation-<span class="hlt">hardened</span> efforts will result in leveraged - not duplicated or independently developed - technology capabilities of: a) Radiation-<span class="hlt">hardened</span>, reconfigurable FPGA-based electronics; and b) High Performance Processors (NOT duplication or independent development).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750026297&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHardening','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750026297&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHardening"><span>Thermoelastic constitutive equations for chemically <span class="hlt">hardening</span> materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shaffer, B. W.; Levitsky, M.</p> <p>1974-01-01</p> <p>Thermoelastic constitutive equations are derived for a material undergoing solidification or <span class="hlt">hardening</span> as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of <span class="hlt">hardening</span>, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20696318','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20696318"><span>'Work-<span class="hlt">Hardenable</span>' Ductile Bulk Metallic Glass</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Das, Jayanta; Eckert, Juergen; Tang Meibo; Wang Weihua; Kim, Ki Buem; Baier, Falko; Theissmann, Ralf</p> <p>2005-05-27</p> <p>Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (<1%) at room temperature. We present a new class of bulk metallic glass, which exhibits high strength of up to 2265 MPa together with extensive 'work <span class="hlt">hardening</span>' and large ductility of 18%. Significant increase in the flow stress was observed during deformation. The 'work-<span class="hlt">hardening</span>' capability and ductility of this class of metallic glass is attributed to a unique structure correlated with atomic-scale inhomogeneity, leading to an inherent capability of extensive shear band formation, interactions, and multiplication of shear bands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JMPSo..59.1731H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JMPSo..59.1731H"><span>Strain <span class="hlt">hardening</span> in bent copper foils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hayashi, Ichiro; Sato, Masumi; Kuroda, Mitsutoshi</p> <p>2011-09-01</p> <p>A series of systematic tensile and microbend tests were conducted on copper foil specimens with different thicknesses. The specimens were made of a copper foil having almost unidirectional crystal orientations that was considered to be nearly single-crystal. In order to investigate the effects of slip system interactions, two different crystal orientations relative to the tensile direction were considered in the tests: one is close to coplanar double-slip orientation, and the other is close to the ideal cube orientation (the tensile direction nearly coincides to [0 0 1]) that yields multi-planar multi-slip deformation. We extended the microbend test method to include the reversal of bending, and we attempted to divide the total amount of strain-<span class="hlt">hardening</span> into isotropic and kinematic <span class="hlt">hardening</span> components. In the tensile tests, no systematic tendency of size dependence was observed. In the microbend tests, size-dependent kinematic <span class="hlt">hardening</span> behavior was observed for both the crystal orientations, while size dependence of isotropic <span class="hlt">hardening</span> was observed only for the multi-planar multi-slip case. We introduce an extended crystal plasticity model that accounts for the effects of the geometrically necessary dislocations (GNDs), which correspond to the spatial gradients of crystallographic slips. Through numerical simulations performed using the model, the origin of the size-dependent behavior observed in the microbend tests is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940004346','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940004346"><span>SEU <span class="hlt">hardening</span> of CMOS memory circuit</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Whitaker, S.; Canaris, J.; Liu, K.</p> <p>1990-01-01</p> <p>This paper reports a design technique to <span class="hlt">harden</span> CMOS memory circuits against Single Event Upset (SEU) in the space environment. A RAM cell and Flip Flop design are presented to demonstrate the method. The Flip Flop was used in the control circuitry for a Reed Solomon encoder designed for the Space Station.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26817383','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26817383"><span>[Microstructural changes in <span class="hlt">hardened</span> beans (Phaseolus vulgaris)].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mujica, Maria Virginia; Granito, Marisela; Soto, Naudy</p> <p>2015-06-01</p> <p>(Phaseolus vulgaris). The <span class="hlt">hardening</span> of Phaseolus vulgaris beans stored at high temperature and high relative humidity is one of the main constraints for consumption. The objective of this research was to evaluate by scanning electron microscopy, structural changes in cotyledons and testa of the <span class="hlt">hardened</span> beans. The freshly harvested grains were stored for twelve months under two conditions: 5 ° C-34% RH and 37 ° C-75% RH, in order to promote <span class="hlt">hardening</span>. The stored raw and cooked grains were lyophilized and fractured. The sections of testa and cotyledons were observed in an electron microscope JSM-6390. After twelve months, grains stored at 37 ° C-75% RH increased their hardness by 503%, whereas there were no significant changes in grains stored at 5 ° C-34% RH. At the microstructural level, the cotyledons of the raw grains show clear differences in appearance of the cell wall, into the intercellular space size and texture matrix protein. There were also differences in compaction of palisade and sub-epidermal layer in the testa of raw grains. After cooking, cotyledon cells of the soft grains were well separated while these ofhard grains were seldom separated. In conclusion, the found differences in hard and soft grains showed a significant participation of both structures, cotyledons and testa, in the grains <span class="hlt">hardening</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27194289','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27194289"><span>'Fire <span class="hlt">hardening</span>' spear wood does slightly <span class="hlt">harden</span> it, but makes it much weaker and more brittle.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ennos, Antony Roland; Chan, Tak Lok</p> <p>2016-05-01</p> <p>It is usually assumed that 'fire <span class="hlt">hardening</span>' the tips of spears, as practised by hunter-gatherers and early Homo spp., makes them harder and better suited for hunting. This suggestion was tested by subjecting coppiced poles of hazel to a fire-<span class="hlt">hardening</span> process and comparing their mechanical properties to those of naturally seasoned poles. A Shore D hardness test showed that fire treatment slightly increased the hardness of the wood, but flexural and impact tests showed that it reduced the strength and work of fracture by 30% and 36%, respectively. These results suggest that though potentially slightly sharper and more durable, fire-<span class="hlt">hardened</span> tips would actually be more likely to break off when used, as may have been the case with the earliest known wooden tool, the Clacton spear. Fire might first have been used to help sharpen the tips of spears, and fire-<span class="hlt">hardening</span> would have been a mostly negative side effect, not its primary purpose.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec58-622.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol3/pdf/CFR-2012-title7-vol3-sec58-622.pdf"><span>7 CFR 58.622 - <span class="hlt">Hardening</span> and storage rooms.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 7 Agriculture 3 2012-01-01 2012-01-01 false <span class="hlt">Hardening</span> and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 <span class="hlt">Hardening</span> and storage rooms. <span class="hlt">Hardening</span> and storage rooms for frozen desserts shall be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec58-622.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol3/pdf/CFR-2010-title7-vol3-sec58-622.pdf"><span>7 CFR 58.622 - <span class="hlt">Hardening</span> and storage rooms.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 7 Agriculture 3 2010-01-01 2010-01-01 false <span class="hlt">Hardening</span> and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 <span class="hlt">Hardening</span> and storage rooms. <span class="hlt">Hardening</span> and storage rooms for frozen desserts shall be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec58-622.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title7-vol3/pdf/CFR-2013-title7-vol3-sec58-622.pdf"><span>7 CFR 58.622 - <span class="hlt">Hardening</span> and storage rooms.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 7 Agriculture 3 2013-01-01 2013-01-01 false <span class="hlt">Hardening</span> and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 <span class="hlt">Hardening</span> and storage rooms. <span class="hlt">Hardening</span> and storage rooms for frozen desserts shall be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec58-622.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title7-vol3/pdf/CFR-2014-title7-vol3-sec58-622.pdf"><span>7 CFR 58.622 - <span class="hlt">Hardening</span> and storage rooms.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... 7 Agriculture 3 2014-01-01 2014-01-01 false <span class="hlt">Hardening</span> and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 <span class="hlt">Hardening</span> and storage rooms. <span class="hlt">Hardening</span> and storage rooms for frozen desserts shall be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec58-622.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol3/pdf/CFR-2011-title7-vol3-sec58-622.pdf"><span>7 CFR 58.622 - <span class="hlt">Hardening</span> and storage rooms.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 7 Agriculture 3 2011-01-01 2011-01-01 false <span class="hlt">Hardening</span> and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 <span class="hlt">Hardening</span> and storage rooms. <span class="hlt">Hardening</span> and storage rooms for frozen desserts shall be...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1876210','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1876210"><span>Continuous in situ measurements of <span class="hlt">volcanic</span> gases with a diode-laser-based spectrometer: CO2 and H2O concentration and <span class="hlt">soil</span> degassing at Vulcano (Aeolian islands: Italy)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>De Rosa, Maurizio; Gagliardi, Gianluca; Rocco, Alessandra; Somma, Renato; De Natale, Paolo; De Natale, Giuseppe</p> <p>2007-01-01</p> <p>We report on a continuous-measurement campaign carried out in Vulcano (Aeolian islands, Sicily), devoted to the simultaneous monitoring of CO2 and H2O concentrations. The measurements were performed with an absorption spectrometer based on a semiconductor laser source emitting around a 2-μm wavelength. The emitted radiation was selectively absorbed by two molecular ro-vibrational transitions specific of the investigated species. Data for CO2 and H2O concentrations, and CO2 <span class="hlt">soil</span> diffusive flux using an accumulation chamber configuration, were collected at several interesting sampling points on the island (Porto Levante beach- PLB, Fossa Grande Crater – FOG- and Valley of Palizzi, PAL). CO2/H2O values, measured on the ground, are very similar (around 0.019 (± 0.006)) and comparable to the previous discrete detected values of 0.213 (Fumarole F5-La Fossa crater rim) and 0.012 (Fumarole VFS – Baia Levante beach) obtaid during the 1977–1993 heating phase of the crater fumaroles. In this work much more homogeneous values are found in different points of the three sites investigated. The field work, although carried out in a limited time window (25th–28th August 2004), pointed out the new apparatus is suitable for continuous gas monitoring of the two species and their ratios, which are important geochemical indicators of <span class="hlt">volcanic</span> activity, for which other reliable continuous monitoring systems are not yet available. PMID:17448243</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014voio.book.....D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014voio.book.....D"><span><span class="hlt">Volcanism</span> on Io</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davies, Ashley Gerard</p> <p>2014-03-01</p> <p>Preface; Introduction; Part I. Io, 1610 to 1995: Galileo to Galileo: 1. Io, 1610-1979; 2. Between Voyager and Galileo: 1979-95; 3. Galileo at Io; Part II. Planetary <span class="hlt">Volcanism</span>: Evolution and Composition: 4. Io and Earth: formation, evolution, and interior structure; 5. Magmas and volatiles; Part III. Observing and Modeling <span class="hlt">Volcanic</span> Activity: 6. Observations: thermal remote sensing of <span class="hlt">volcanic</span> activity; 7. Models of effusive eruption processes; 8. Thermal evolution of <span class="hlt">volcanic</span> eruptions; Part IV. Galileo at Io: the <span class="hlt">Volcanic</span> Bestiary: 9. The view from Galileo; 10. The lava lake at Pele; 11. Pillan and Tvashtar: lava fountains and flows; 12. Prometheus and Amirani: Effusive activity and insulated flows; 13. Loki Patera: Io's powerhouse; 14. Other volcanoes and eruptions; Part V. <span class="hlt">Volcanism</span> on Io: The Global View: 15. Geomorphology: paterae, shields, flows and mountains; 16. <span class="hlt">Volcanic</span> plumes; 17. Hot spots; Part VI. Io after Galileo: 18. <span class="hlt">Volcanism</span> on Io: a post-Galileo view; 19. The future of Io observations; Appendix 1; Appendix 2; References; Index.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007voio.book.....D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007voio.book.....D"><span><span class="hlt">Volcanism</span> on Io</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davies, Ashley Gerard</p> <p>2007-08-01</p> <p>Preface; Introduction; Part I. Io, 1610 to 1995: Galileo to Galileo: 1. Io, 1610-1979; 2. Between Voyager and Galileo: 1979-1995; 3. Galileo at Io; Part II. Planetary <span class="hlt">Volcanism</span>: Evolution and Composition: 4. Io and Earth: formation, evolution, and interior structure; 5. Magmas and volatiles; Part III. Observing and Modeling <span class="hlt">Volcanic</span> Activity: 6. Observations: thermal remote sensing of <span class="hlt">volcanic</span> activity; 7. Models of effusive eruption processes; 8. Thermal evolution of <span class="hlt">volcanic</span> eruptions; Part IV. Galileo at Io: the <span class="hlt">Volcanic</span> Bestiary: 9. The view from Galileo; 10. The lava lake at Pele; 11. Pillan and Tvashtar: lava fountains and flows; 12. Prometheus and Amirani: Effusive activity and insulated flows; 13. Loki Patera: Io's powerhouse; 14. Other volcanoes and eruptions; Part V. <span class="hlt">Volcanism</span> on Io: The Global View: 15. Geomorphology: paterae, shields, flows and mountains; 16. <span class="hlt">Volcanic</span> plumes; 17. Hot spots; Part VI. Io after Galileo: 18. <span class="hlt">Volcanism</span> on Io: a post-Galileo view; 19. The future of Io observations; Appendix 1; Appendix 2; References; Index.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5723M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5723M"><span>Tellurium in active <span class="hlt">volcanic</span> environments: Preliminary results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Milazzo, Silvia; Calabrese, Sergio; D'Alessandro, Walter; Brusca, Lorenzo; Bellomo, Sergio; Parello, Francesco</p> <p>2014-05-01</p> <p>Tellurium is a toxic metalloid and, according to the Goldschmidt classification, a chalcophile element. In the last years its commercial importance has considerably increased because of its wide use in solar cells, thermoelectric and electronic devices of the last generation. Despite such large use, scientific knowledge about volcanogenic tellurium is very poor. Few previous authors report result of tellurium concentrations in <span class="hlt">volcanic</span> plume, among with other trace metals. They recognize this element as volatile, concluding that <span class="hlt">volcanic</span> gases and sulfur deposits are usually enriched with tellurium. Here, we present some results on tellurium concentrations in <span class="hlt">volcanic</span> emissions (plume, fumaroles, ash leachates) and in environmental matrices (<span class="hlt">soils</span> and plants) affected by <span class="hlt">volcanic</span> emissions and/or deposition. Samples were collected at Etna and Vulcano (Italy), Turrialba (Costa Rica), Miyakejima, Aso, Asama (Japan), Mutnovsky (Kamchatka) at the crater rims by using common filtration techniques for aerosols (polytetrafluoroethylene filters). Filters were both eluted with Millipore water and acid microwave digested, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). <span class="hlt">Volcanic</span> ashes emitted during explosive events on Etna and Copahue (Argentina) were analyzed for tellurium bulk composition and after leaching experiments to evaluate the soluble fraction of tellurium. <span class="hlt">Soils</span> and leaves of vegetation were also sampled close to active <span class="hlt">volcanic</span> vents (Etna, Vulcano, Nisyros, Nyiragongo, Turrialba, Gorely and Masaya) and investigated for tellurium contents. Preliminary results showed very high enrichments of tellurium in <span class="hlt">volcanic</span> emissions comparing with other volatile elements like mercury, arsenic, thallium and bismuth. This suggests a primary transport in the volatile phase, probably in gaseous form (as also suggested by recent studies) and/or as soluble salts (halides and/or sulfates) adsorbed on the surface of particulate particles and ashes. First</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..177a2144K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..177a2144K"><span>Structural heredity influence upon principles of strain wave <span class="hlt">hardening</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kiricheck, A. V.; Barinov, S. V.; Yashin, A. V.</p> <p>2017-02-01</p> <p>It was established experimentally that by penetration of a strain wave through material <span class="hlt">hardened</span> not only the technological modes of processing, but also a technological heredity - the direction of the fibers of the original macrostructure have an influence upon the diagram of microhardness. By penetration of the strain wave along fibers, the degree of <span class="hlt">hardening</span> the material is less, however, a product is <span class="hlt">hardened</span> throughout its entire section mainly along fibers. In the direction of the strain waves across fibers of the original structure of material, the degree of material <span class="hlt">hardening</span> is much higher, the depth of the <span class="hlt">hardened</span> layer with the degree of <span class="hlt">hardening</span> not less than 50% makes at least 3 mm. It was found that under certain conditions the strain wave can completely change the original structure of the material. Thus, a heterogeneously <span class="hlt">hardened</span> structure characterized by the interchange of harder and more viscous areas is formed, which is beneficial for assurance of high operational properties of material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998APS..GECOWP401I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998APS..GECOWP401I"><span>Plasma <span class="hlt">hardening</span> of railway wheel surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Isakaev, E. Kh.; Ivanov, P. P.; Tyuftyaev, A. S.; Paristyi, I. L.; Troitsky, A. A.; Yablonsky, A. E.; Filippov, G. A.</p> <p>1998-10-01</p> <p>A computer-controlled plasma technology was developed for the treatment of rolling stock wheels, providing the thermal <span class="hlt">hardening</span> of tread and flange working surfaces. As a result of the plasma treatment the surface hardness of the wheel grows from 255 up to 420-450 HB. Herewith, the wear capability of the wheel metal grows 2-3 times and its resistance to the weariness-driven destruction grows 1.5 times due to the pecularities of the structural state of the steel, arising out of the thermal impact and of the alloying of the steel with nitrogen during the plasma treatment. Installation of several plants based on this technology in engine houses allowed to carry out a full scale experiment in order to assess the running characteristics of treated wheel sets in comparison with plain ones. Wheel life between mounting and truing or dismounting doubles due to plasma <span class="hlt">hardening</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21139579','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21139579"><span>Cyclic <span class="hlt">hardening</span> in bundled actin networks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schmoller, K M; Fernández, P; Arevalo, R C; Blair, D L; Bausch, A R</p> <p>2010-01-01</p> <p>Nonlinear deformations can irreversibly alter the mechanical properties of materials. Most soft materials, such as rubber and living tissues, display pronounced softening when cyclically deformed. Here we show that, in contrast, reconstituted networks of crosslinked, bundled actin filaments <span class="hlt">harden</span> when subject to cyclical shear. As a consequence, they exhibit a mechano-memory where a significant stress barrier is generated at the maximum of the cyclic shear strain. This unique response is crucially determined by the network architecture: at lower crosslinker concentrations networks do not <span class="hlt">harden</span>, but soften showing the classic Mullins effect known from rubber-like materials. By simultaneously performing macrorheology and confocal microscopy, we show that cyclic shearing results in structural reorganization of the network constituents such that the maximum applied strain is encoded into the network architecture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/919904','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/919904"><span>Radiation-<span class="hlt">hardened</span> transistor and integrated circuit</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ma, Kwok K.</p> <p>2007-11-20</p> <p>A composite transistor is disclosed for use in radiation <span class="hlt">hardening</span> a CMOS IC formed on an SOI or bulk semiconductor substrate. The composite transistor has a circuit transistor and a blocking transistor connected in series with a common gate connection. A body terminal of the blocking transistor is connected only to a source terminal thereof, and to no other connection point. The blocking transistor acts to prevent a single-event transient (SET) occurring in the circuit transistor from being coupled outside the composite transistor. Similarly, when a SET occurs in the blocking transistor, the circuit transistor prevents the SET from being coupled outside the composite transistor. N-type and P-type composite transistors can be used for each and every transistor in the CMOS IC to radiation <span class="hlt">harden</span> the IC, and can be used to form inverters and transmission gates which are the building blocks of CMOS ICs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20072355','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20072355"><span>Hologram formation in <span class="hlt">hardened</span> dichromated gelatin films.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lin, L H</p> <p>1969-05-01</p> <p><span class="hlt">Hardened</span> gelatin films sensitized with ammonium dichromate can be utilized to record high quality holograms. The maximum diffraction efficiency of the hologram approaches 90%. The light scattering from the hologram is so low that under ordinary light the hologram plate appears almost indistinguishable from a clear glass plate. Either a transmission or a reflection hologram can be recorded. Linear recording range of light amplitude is large. A practical method of preparing and processing the film is described, and the exposure characteristics are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/750456','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/750456"><span>Pulsed laser surface <span class="hlt">hardening</span> of ferrous alloys.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Xu, Z.; Reed, C. B.; Leong, K. H.; Hunter, B. V.</p> <p>1999-09-30</p> <p>A high power pulsed Nd:YAG laser and special optics were used to produce surface <span class="hlt">hardening</span> on 1045 steel and gray cast iron by varying the process parameters. Unlike CO{sub 2} lasers, where absorptive coatings are required, the higher absorptivity of ferrous alloys at the Nd:YAG laser wavelength eliminates the necessity of applying a coating before processing. Metallurgical analysis of the treated tracks showed that very fine and hard martensitic microstructure (1045 steel) or inhomogeneous martensite (gray cast iron) were obtained without surface melting, giving maximum hardness of HRC 61 and HRC 40 for 1045 steel and gray cast iron respectively. The corresponding maximum case depths for both alloys at the above hardness are 0.6 mm. Gray cast iron was more difficult to <span class="hlt">harden</span> without surface melting because of its lower melting temperature and a significantly longer time-at-temperature required to diffuse carbon atoms from the graphite flakes into the austenite matrix during laser heating. The thermal distortion was characterized in term of flatness changes after surface <span class="hlt">hardening</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/895419','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/895419"><span>Dislocation Multi-junctions and Strain <span class="hlt">Hardening</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T</p> <p>2006-06-20</p> <p>At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain <span class="hlt">hardening</span>: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain <span class="hlt">hardening</span> to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain <span class="hlt">hardening</span> in BCC crystals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16641992','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16641992"><span>Dislocation multi-junctions and strain <span class="hlt">hardening</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bulatov, Vasily V; Hsiung, Luke L; Tang, Meijie; Arsenlis, Athanasios; Bartelt, Maria C; Cai, Wei; Florando, Jeff N; Hiratani, Masato; Rhee, Moon; Hommes, Gregg; Pierce, Tim G; de la Rubia, Tomas Diaz</p> <p>2006-04-27</p> <p>At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects called dislocations. First proposed theoretically in 1934 (refs 1-3) to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain <span class="hlt">hardening</span>, a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain <span class="hlt">hardening</span> to pair-wise dislocation reactions in which two intersecting dislocations form junctions that tie the dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed 'multi-junctions'. We first predict the existence of multi-junctions using dislocation dynamics and atomistic simulations and then confirm their existence by transmission electron microscopy experiments in single-crystal molybdenum. In large-scale dislocation dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication, thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain <span class="hlt">hardening</span> in body-centred cubic crystals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..MARH19011R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..MARH19011R"><span>Strain <span class="hlt">Hardening</span> in Bidisperse Polymer Glasses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robbins, Mark O.; Hoy, Robert S.</p> <p>2009-03-01</p> <p>The connections between glassy and rubbery strain <span class="hlt">hardening</span> have been a matter of great controversy in recent years. Recent experiments and our earlier simulations have suggested that the <span class="hlt">hardening</span> modulus GR is proportional to the entanglement density in glasses, as it is to the crosslink density in rubbers. In this work we present more extensive studies of strain <span class="hlt">hardening</span> in bidisperse glasses and its relation to microscopic conformational changes. The mixtures contain chains of very different lengths but equivalent chemistry. GR does not scale simply with the entanglement density. Instead it obeys a simple mixing rule, with GR equal to the volume fraction weighted average of the moduli of the two pure components. As in recent studies of monodisperse systems (R. S. Hoy and M. O. Robbins, Phys. Rev. Lett. 99, 117801 (2007)), the stress is directly correlated to the degree of chain orientation. Chains of a given length undergo almost the same degree of alignment in pure systems and mixtures, explaining why the simple mixing rule applies. The connection to recent analytic theories by K. Chen and K. S. Schweizer (PRL, in press) will be discussed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6858430','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6858430"><span>Stage IV work <span class="hlt">hardening</span> in cubic metals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rollett, A.D.; Kocks, U.F.; Doherty, R.D.</p> <p>1986-01-01</p> <p>The work <span class="hlt">hardening</span> of fcc metals at large strains is discussed with reference to the linear stress-strain behavior often observed at large strains and known as Stage IV. The experimental evidence shows that Stage IV is a work <span class="hlt">hardening</span> phenomenon that is found quite generally, even in pure fcc metals subjected to homogeneous deformation. A simple model for Stage IV in pure metals is presented, based on the accumulation of dislocation debris. Experiments are described for large strain torsion tests on four aluminum alloys. The level and extent of Stage IV scaled with the saturation stress that would represent the end of Stage III in the absence of a Stage IV. Reversing the torsion after large prestrains produced transient reductions in the work <span class="hlt">hardening</span>. The strain rate sensitivity was also measured before and during the transient and found not to vary significantly. The microstructure observed at large strains in an Mg alloy suggest that Stage IV can occur in the absence of microband formation. Previous proposals for the cause of Stage IV are reviewed and found to be not supported by recent experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160000375&hterms=property&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dproperty','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160000375&hterms=property&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dproperty"><span><span class="hlt">Volcanic</span> Aerosol Radiative Properties</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lacis, Andrew</p> <p>2015-01-01</p> <p>Large sporadic <span class="hlt">volcanic</span> eruptions inject large amounts of sulfur bearing gases into the stratosphere which then get photochemically converted to sulfuric acid aerosol droplets that exert a radiative cooling effect on the global climate system lasting for several years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22096777','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22096777"><span>Empirical beam <span class="hlt">hardening</span> correction (EBHC) for CT</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc</p> <p>2010-10-15</p> <p>Purpose: Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam <span class="hlt">hardening</span> artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam <span class="hlt">hardening</span> artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam <span class="hlt">hardening</span> correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam <span class="hlt">hardening</span> in single energy CT data. Methods: The only a priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material-specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone-beam dual-source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual-source micro-CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EurSS..49...15Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EurSS..49...15Z"><span>Radiogeochemistry of Kamchatka <span class="hlt">soils</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zakharikhina, L. V.; Litvinenko, Yu. S.</p> <p>2016-01-01</p> <p>Background concentrations of Th and U in <span class="hlt">volcanic</span> <span class="hlt">soils</span> (Andosols) of Kamchatka are much lower than their clarkes in continental <span class="hlt">soils</span>. The dose rate of gamma radiation above the <span class="hlt">soil</span> surface (10-11.5 µR/h in the south and 8-9.5 [m]R/h in the north of Kamchatka Peninsula) is lower than the natural level of this index for the mountainous areas in the boreal zone of Russia. The natural radiogeochemical background of Kamchatka <span class="hlt">soils</span> is controlled by the petrochemical composition of <span class="hlt">volcanic</span> ash composing the mineral basis of Kamchatka <span class="hlt">soils</span>. It is higher in the southern <span class="hlt">soil</span> province, where <span class="hlt">soils</span> develop from acidic ashes, in comparison with the northern province, with a predominance of <span class="hlt">soils</span> developing from ashes of basic and intermediate composition. This agrees with Th and U clarkes for the corresponding types of <span class="hlt">volcanic</span> rocks and explains the natural origin of the elevated radiogeochemical background in the southern part of Kamchatka as compared with its northern part. The <span class="hlt">soils</span> of the northern province developing from relatively fresh <span class="hlt">volcanic</span> ashes show a lower Th/U ratio as compared to the <span class="hlt">soils</span> of southern Kamchatka because of higher uranium content in the newly deposited ashes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1025989','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1025989"><span>Modeling <span class="hlt">volcanic</span> ash dispersal</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p></p> <p>2010-10-22</p> <p>Explosive <span class="hlt">volcanic</span> eruptions inject into the atmosphere large amounts of <span class="hlt">volcanic</span> material (ash, blocks and lapilli). Blocks and larger lapilli follow ballistic and non-ballistic trajectories and fall rapidly close to the volcano. In contrast, very fine ashes can remain entrapped in the atmosphere for months to years, and may affect the global climate in the case of large eruptions. Particles having sizes between these two end-members remain airborne from hours to days and can cover wide areas downwind. Such <span class="hlt">volcanic</span> fallout entails a serious threat to aircraft safety and can create many undesirable effects to the communities located around the volcano. The assessment of <span class="hlt">volcanic</span> fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard scenarios and/or to give short-term forecasts during emergency situations. This talk will be focused on the main aspects related to modeling <span class="hlt">volcanic</span> ash dispersal and fallout with application to the well known problem created by the Eyjafjöll volcano in Iceland. Moreover, a short description of the main <span class="hlt">volcanic</span> monitoring techniques is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/sciencecinema/biblio/1025989','SCIGOVIMAGE-SCICINEMA'); return false;" href="http://www.osti.gov/sciencecinema/biblio/1025989"><span>Modeling <span class="hlt">volcanic</span> ash dispersal</span></a></p> <p><a target="_blank" href="http://www.osti.gov/sciencecinema/">ScienceCinema</a></p> <p>None</p> <p>2016-07-12</p> <p>Explosive <span class="hlt">volcanic</span> eruptions inject into the atmosphere large amounts of <span class="hlt">volcanic</span> material (ash, blocks and lapilli). Blocks and larger lapilli follow ballistic and non-ballistic trajectories and fall rapidly close to the volcano. In contrast, very fine ashes can remain entrapped in the atmosphere for months to years, and may affect the global climate in the case of large eruptions. Particles having sizes between these two end-members remain airborne from hours to days and can cover wide areas downwind. Such <span class="hlt">volcanic</span> fallout entails a serious threat to aircraft safety and can create many undesirable effects to the communities located around the volcano. The assessment of <span class="hlt">volcanic</span> fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard scenarios and/or to give short-term forecasts during emergency situations. This talk will be focused on the main aspects related to modeling <span class="hlt">volcanic</span> ash dispersal and fallout with application to the well known problem created by the Eyjafjöll volcano in Iceland. Moreover, a short description of the main <span class="hlt">volcanic</span> monitoring techniques is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21516729','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21516729"><span>Constitutive modelling of evolving flow anisotropy including distortional <span class="hlt">hardening</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pietryga, Michael P.; Vladimirov, Ivaylo N.; Reese, Stefanie</p> <p>2011-05-04</p> <p>The paper presents a new constitutive model for anisotropic metal plasticity that takes into account the expansion or contraction (isotropic <span class="hlt">hardening</span>), translation (kinematic <span class="hlt">hardening</span>) and change of shape (distortional <span class="hlt">hardening</span>) of the yield surface. The experimentally observed region of high curvature ('nose') on the yield surface in the loading direction and flattened shape in the reverse loading direction are modelled here by means of the concept of directional distortional <span class="hlt">hardening</span>. The modelling of directional distortional <span class="hlt">hardening</span> is accomplished by means of an evolving fourth-order tensor. The applicability of the model is illustrated by fitting experimental subsequent yield surfaces at finite plastic deformation. Comparisons with test data for aluminium low and high work <span class="hlt">hardening</span> alloys display a good agreement between the simulation results and the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA09334&hterms=Volcanic+Eruptions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DVolcanic%2BEruptions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA09334&hterms=Volcanic+Eruptions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DVolcanic%2BEruptions"><span><span class="hlt">Volcanic</span> Eruptions in Kamchatka</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2007-01-01</p> <p>[figure removed for brevity, see original site] [figure removed for brevity, see original site] Sheveluch Stratovolcano Click on the image for full resolution TIFF Klyuchevskoy Stratovolcano Click on the image for full resolution TIFF <p/> One of the most <span class="hlt">volcanically</span> active regions of the world is the Kamchatka Peninsula in eastern Siberia, Russia. It is not uncommon for several volcanoes to be erupting at the same time. On April 26, 2007, the Advanced Spaceborne Thermal Emission and Reflection Radioneter (ASTER) on NASA's Terra spacecraft captured these images of the Klyuchevskoy and Sheveluch stratovolcanoes, erupting simultaneously, and 80 kilometers (50 miles) apart. Over Klyuchevskoy, the thermal infrared data (overlaid in red) indicates that two open-channel lava flows are descending the northwest flank of the volcano. Also visible is an ash-and-water plume extending to the east. Sheveluch volcano is partially cloud-covered. The hot flows highlighted in red come from a lava dome at the summit. They are avalanches of material from the dome, and pyroclastic flows. <p/> 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. <p/> ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra spacecraft. 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. <p/> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070025090&hterms=glass&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dglass','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070025090&hterms=glass&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dglass"><span>Surface Coatings on Lunar <span class="hlt">Volcanic</span> Glasses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wentworth, Susan J.; McKay, D. S.; Thomas,-Keprta, K. L.; Clemett, S. J.</p> <p>2007-01-01</p> <p>We are undertaking a detailed study of surface deposits on lunar <span class="hlt">volcanic</span> glass beads. These tiny deposits formed by vapor condensation during cooling of the gases that drove the fire fountain eruptions responsible for the formation of the beads. <span class="hlt">Volcanic</span> glass beads are present in most lunar <span class="hlt">soil</span> samples in the returned lunar collection. The mare-composition beads formed as a result of fire-fountaining approx.3.4-3.7 Ga ago, within the age range of large-scale mare <span class="hlt">volcanism</span>. Some samples from the Apollo 15 and Apollo 17 landing sites are enriched in <span class="hlt">volcanic</span> spherules. Three major types of <span class="hlt">volcanic</span> glass bead have been identified: Apollo 15 green glass, Apollo 17 orange glass, and Apollo 17 "black" glass. The Apollo 15 green glass has a primitive composition with low Ti. The high-Ti compositions of the orange and black glasses are essentially identical to each other but the black glasses are opaque because of quench crystallization. A poorly understood feature common to the Apollo 15 and 17 <span class="hlt">volcanic</span> glasses is the presence of small deposits of unusual materials on their exterior surfaces. For example, early studies indicated that the Apollo 17 orange glasses had surface enrichments of In, Cd, Zn, Ga, Ge, Au, and Na, and possible Pb- and Zn-sulfides, but it was not possible to characterize the surface features in detail. Technological advances now permit us to examine such features in detail. Preliminary FE-TEM/X-ray studies of ultramicrotome sections of Apollo 15 green glass indicate that the surface deposits are heterogeneous and layered, with an inner layer consisting of Fe with minor S and an outer layer of Fe and no S, and scattered Zn enrichments. Layering in surface deposits has not been identified previously; it will be key to defining the history of lunar fire fountaining.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5953052','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5953052"><span>Radiation-<span class="hlt">hardened</span> nonvolatile MNOS RAM</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wrobel, T.F.; Dodson, W.H.; Hash, G.L.; Jones, R.V.; Nasby, R.D.; Olson, R.J.</p> <p>1983-01-01</p> <p>A radiation <span class="hlt">hardened</span> nonvolatile MNOS RAM is being developed at Sandia National Laboratories. The memory organization is 128 x 8 bits and utilizes two p-channel MNOS transistors per memory cell. The peripheral circuitry is constructed with CMOS metal gate and is processed with standard Sandia rad-hard processing techniques. The devices have memory retention after a dose-rate exposure of 1E12 rad(Si)/s, are functional after total dose exposure of 1E6 rad(Si), and are dose-rate upset resistant to levels of 7E8 rad(Si)/s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983ITNS...30.4270W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983ITNS...30.4270W"><span>A radiation <span class="hlt">hardened</span> nonvolatile MNOS RAM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wrobel, T. F.; Dodson, W. H.; Hash, G. L.; Jones, R. V.; Nasby, R. D.; Olson, R. J.</p> <p>1983-12-01</p> <p>A radiation <span class="hlt">hardened</span> nonvolatile MNOS RAM (SA2998) is being developed at Sandia National Laboratories. The memory organization is 128 x 8 bits and utilizes two p-channel MNOS transistors per memory cell. The peripheral circuitry is constructed with CMOS metal gate and is processed with standard Sandia rad-hard processing techniques. The device requires +10 V and +25 V for operation. The devices have memory retention after a dose-rate exposure of 1E12 rad(Si)/s, are functional after total dose exposure of 1E6 rad(Si), and are dose-rate upset resistant to levels of 7E8 rad(Si)/s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5475272','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5475272"><span>Strain <span class="hlt">hardening</span> of steel EP836</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lyadskaya, A.A.; Lappa, R.M.; Spuskanyuk, V.Z.</p> <p>1986-03-01</p> <p>The authors investigate the effect of different combinations of cold hydraulic pressing and heat treatment on the physical and mechanical properties of steel EP836 (03N17K10V10MT), containing 0.03% C, 16-17% Ni, 10-11.5% Co, 9.5-11.5% W, 1% Ti, 1% Mo, and 0.15% A1. Deformation of the unaged steel resulted in insignificant <span class="hlt">hardening</span> without a decrease in plasticity; this agrees with the results of investigations of other steels of this class.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/920878','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/920878"><span>Enabling Strain <span class="hlt">Hardening</span> Simulations with Dislocation Dynamics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Arsenlis, A; Cai, W</p> <p>2006-12-20</p> <p>Numerical algorithms for discrete dislocation dynamics simulations are investigated for the purpose of enabling strain <span class="hlt">hardening</span> simulations of single crystals on massively parallel computers. The algorithms investigated include the /(N) calculation of forces, the equations of motion, time integration, adaptive mesh refinement, the treatment of dislocation core reactions, and the dynamic distribution of work on parallel computers. A simulation integrating all of these algorithmic elements using the Parallel Dislocation Simulator (ParaDiS) code is performed to understand their behavior in concert, and evaluate the overall numerical performance of dislocation dynamics simulations and their ability to accumulate percents of plastic strain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060015096','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060015096"><span>Expecting the Unexpected: Radiation <span class="hlt">Hardened</span> Software</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Penix, John; Mehlitz, Peter C.</p> <p>2005-01-01</p> <p>Radiation induced Single Event Effects (SEEs) are a serious problem for spacecraft flight software, potentially leading to a complete loss of mission. Conventional risk mitigation has been focused on hardware, leading to slow, expensive and outdated on-board computing devices, increased power consumption and launch mass. Our approach is to look at SEEs from a software perspective, and to explicitly design flight software so that it can detect and correct the majority of SEES. Radiation <span class="hlt">hardened</span> flight software will reduce the significant residual residual risk for critical missions and flight phases, and enable more use of inexpensive and fast COTS hardware.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080032798','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080032798"><span>Technology Developments in Radiation-<span class="hlt">Hardened</span> Electronics for Space Environments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keys, Andrew S.; Howell, Joe T.</p> <p>2008-01-01</p> <p>The Radiation <span class="hlt">Hardened</span> Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation <span class="hlt">hardened</span> and low temperature electronics technologies. Three approaches are being taken to address radiation <span class="hlt">hardening</span>: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS, Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation <span class="hlt">hardening</span>, low temperature extremes are addressed with a focus on material and design approaches. System level applications for the RHESE technology products are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70035662','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70035662"><span><span class="hlt">Volcanic</span> hazards to airports</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Guffanti, M.; Mayberry, G.C.; Casadevall, T.J.; Wunderman, R.</p> <p>2009-01-01</p> <p><span class="hlt">Volcanic</span> activity has caused significant hazards to numerous airports worldwide, with local to far-ranging effects on travelers and commerce. Analysis of a new compilation of incidents of airports impacted by <span class="hlt">volcanic</span> activity from 1944 through 2006 reveals that, at a minimum, 101 airports in 28 countries were affected on 171 occasions by eruptions at 46 volcanoes. Since 1980, five airports per year on average have been affected by <span class="hlt">volcanic</span> activity, which indicates that <span class="hlt">volcanic</span> hazards to airports are not rare on a worldwide basis. The main hazard to airports is ashfall, with accumulations of only a few millimeters sufficient to force temporary closures of some airports. A substantial portion of incidents has been caused by ash in airspace in the vicinity of airports, without accumulation of ash on the ground. On a few occasions, airports have been impacted by hazards other than ash (pyroclastic flow, lava flow, gas emission, and phreatic explosion). Several airports have been affected repeatedly by <span class="hlt">volcanic</span> hazards. Four airports have been affected the most often and likely will continue to be among the most vulnerable owing to continued nearby <span class="hlt">volcanic</span> activity: Fontanarossa International Airport in Catania, Italy; Ted Stevens Anchorage International Airport in Alaska, USA; Mariscal Sucre International Airport in Quito, Ecuador; and Tokua Airport in Kokopo, Papua New Guinea. The USA has the most airports affected by <span class="hlt">volcanic</span> activity (17) on the most occasions (33) and hosts the second highest number of volcanoes that have caused the disruptions (5, after Indonesia with 7). One-fifth of the affected airports are within 30 km of the source volcanoes, approximately half are located within 150 km of the source volcanoes, and about three-quarters are within 300 km; nearly one-fifth are located more than 500 km away from the source volcanoes. The volcanoes that have caused the most impacts are Soufriere Hills on the island of Montserrat in the British West Indies</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960050123','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960050123"><span><span class="hlt">Volcanism</span> in Eastern Africa</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cauthen, Clay; Coombs, Cassandra R.</p> <p>1996-01-01</p> <p>In 1891, the Virunga Mountains of Eastern Zaire were first acknowledged as volcanoes, and since then, the Virunga Mountain chain has demonstrated its potentially violent <span class="hlt">volcanic</span> nature. The Virunga Mountains lie across the Eastern African Rift in an E-W direction located north of Lake Kivu. Mt. Nyamuragira and Mt. Nyiragongo present the most hazard of the eight mountains making up Virunga <span class="hlt">volcanic</span> field, with the most recent activity during the 1970-90's. In 1977, after almost eighty years of moderate activity and periods of quiescence, Mt. Nyamuragira became highly active with lava flows that extruded from fissures on flanks circumscribing the volcano. The flows destroyed vast areas of vegetation and Zairian National Park areas, but no casualties were reported. Mt. Nyiragongo exhibited the same type <span class="hlt">volcanic</span> activity, in association with regional tectonics that effected Mt. Nyamuragira, with variations of lava lake levels, lava fountains, and lava flows that resided in Lake Kivu. Mt. Nyiragongo, recently named a Decade volcano, presents both a direct and an indirect hazard to the inhabitants and properties located near the volcano. The Virunga volcanoes pose four major threats: <span class="hlt">volcanic</span> eruptions, lava flows, toxic gas emission (CH4 and CO2), and earthquakes. Thus, the volcanoes of the Eastern African <span class="hlt">volcanic</span> field emanate harm to the surrounding area by the forecast of <span class="hlt">volcanic</span> eruptions. During the JSC Summer Fellowship program, we will acquire and collate remote sensing, photographic (Space Shuttle images), topographic and field data. In addition, maps of the extent and morphology(ies) of the features will be constructed using digital image information. The database generated will serve to create a Geographic Information System for easy access of information of the Eastem African <span class="hlt">volcanic</span> field. The analysis of <span class="hlt">volcanism</span> in Eastern Africa will permit a comparison for those areas from which we have field data. Results from this summer's work will permit</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.T52C..01G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.T52C..01G"><span><span class="hlt">Volcanic</span> Versus Non-<span class="hlt">Volcanic</span> Passive Margins: Two Different Ways to Break-up Continents</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Geoffroy, L.; Burov, E. B.; Werner, P.; Unternehr, P.</p> <p>2014-12-01</p> <p><span class="hlt">Volcanic</span> passive margins (VPMs) are distinctive features of Larges Igneous Provinces. They characterize continental breakup associated with the extrusion and intrusion of large volumes of magma, predominantly mafic. In Large Igneous Provinces, regional fissural <span class="hlt">volcanism</span> predates localized syn-magmatic break-up of the lithosphere, suggesting that mantle melting is a cause of continental break-up, not a consequence. Early melt covers as <span class="hlt">volcanic</span> traps large cratonic or/and cratonic-edge continental areas. Crustal dilatation through dyking in the upper crust and magma underplating at Moho level is thought to occur massively during this early stage. Lithosphere extension leading to break-up and VPMs development is coeval with a 3D focusing of mantle melting, giving rise to VPMs. From a combination of deep seismic reflection profiles and onshore observations, we show that the mechanism of continental breakup at <span class="hlt">volcanic</span> passive margins is very different from the one generally proposed for non-magmatic systems. Crustal extension and coeval extrusion of thick wedges of seaward-dipping basalts are accommodated by continentward-dipping detachment-faults at both conjugate margins. Those faults root on a deformed ductile crust whose composition seems partly magmatic. Our numerical modeling show that <span class="hlt">hardening</span> of deep continental crust during the early magmatic stages provokes a divergent flow of the ductile lithosphere (mantle and lower crust) away from a central continental block which thins through advection with time. Magma-assisted crustal-scale faults dipping continentward root over this flowing material, isolating micro-continents which may be lost in the future oceanic domain. The structure and tectonic evolution of <span class="hlt">volcanic</span> passive margins cannot therefore be compared to non-<span class="hlt">volcanic</span> ones, where major detachment faults dip oceanward during the necking-stage and where mantle is finally exhumed during the mechanical breakup. Confusions may exist where ancient hyper</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140005237','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140005237"><span>Organic Entrainment and Preservation in <span class="hlt">Volcanic</span> Glasses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilhelm, Mary Beth; Ojha, Lujendra; Brunner, Anna E.; Dufek, Josef D.; Wray, James Joseph</p> <p>2014-01-01</p> <p>Unaltered pyroclastic deposits have previously been deemed to have "low" potential for the formation, concentration and preservation of organic material on the Martian surface. Yet <span class="hlt">volcanic</span> glasses that have solidified very quickly after an eruption may be good candidates for containment and preservation of refractory organic material that existed in a biologic system pre-eruption due to their impermeability and ability to attenuate UV radiation. Analysis using NanoSIMS of <span class="hlt">volcanic</span> glass could then be performed to both deduce carbon isotope ratios that indicate biologic origin and confirm entrainment during eruption. Terrestrial contamination is one of the biggest barriers to definitive Martian organic identification in <span class="hlt">soil</span> and rock samples. While there is a greater potential to concentrate organics in sedimentary strata, <span class="hlt">volcanic</span> glasses may better encapsulate and preserve organics over long time scales, and are widespread on Mars. If <span class="hlt">volcanic</span> glass from many sites on Earth could be shown to contain biologically derived organics from the original environment, there could be significant implications for the search for biomarkers in ancient Martian environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SPIE.9033E..41L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9033E..41L"><span>Beam <span class="hlt">hardening</span> and partial beam <span class="hlt">hardening</span> of the bowtie filter: Effects on dosimetric applications in CT</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lopez-Rendon, X.; Zhang, G.; Bosmans, H.; Oyen, R.; Zanca, F.</p> <p>2014-03-01</p> <p>Purpose: To estimate the consequences on dosimetric applications when a CT bowtie filter is modeled by means of full beam <span class="hlt">hardening</span> versus partial beam <span class="hlt">hardening</span>. Method: A model of source and filtration for a CT scanner as developed by Turner et. al. [1] was implemented. Specific exposures were measured with the stationary CT X-ray tube in order to assess the equivalent thickness of Al of the bowtie filter as a function of the fan angle. Using these thicknesses, the primary beam attenuation factors were calculated from the energy dependent photon mass attenuation coefficients and used to include beam <span class="hlt">hardening</span> in the spectrum. This was compared to a potentially less computationally intensive approach, which accounts only partially for beam <span class="hlt">hardening</span>, by giving the photon spectrum a global (energy independent) fan angle specific weighting factor. Percentage differences between the two methods were quantified by calculating the dose in air after passing several water equivalent thicknesses representative for patients having different BMI. Specifically, the maximum water equivalent thickness of the lateral and anterior-posterior dimension and of the corresponding (half) effective diameter were assessed. Results: The largest percentage differences were found for the thickest part of the bowtie filter and they increased with patient size. For a normal size patient they ranged from 5.5% at half effective diameter to 16.1% for the lateral dimension; for the most obese patient they ranged from 7.7% to 19.3%, respectively. For a complete simulation of one rotation of the x-ray tube, the proposed method was 12% faster than the complete simulation of the bowtie filter. Conclusion: The need for simulating the beam <span class="hlt">hardening</span> of the bow tie filter in Monte Carlo platforms for CT dosimetry will depend on the required accuracy.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006SPIE.6119..111B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006SPIE.6119..111B"><span>CID25: radiation <span class="hlt">hardened</span> color video camera</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baiko, D. A.; Bhaskaran, S. K.; Czebiniak, S. W.</p> <p>2006-02-01</p> <p>The charge injection device, CID25, is presented. The CID25 is a color video imager. The imager is compliant with the NTSC interlaced TV standard. It has 484 by 710 displayable pixels and is capable of producing 30 frames-per-second color video. The CID25 is equipped with the preamplifier-per-pixel technology combined with parallel row processing to achieve high conversion gain and low noise bandwidth. The on-chip correlated double sampling circuitry serves to reduce the low frequency noise components. The CID25 is operated by a camera system consisting of two parts, the head assembly and the camera control unit (CCU). The head assembly and the CCU can be separated by up to 150 meter long cable. The CID25 imager and the head portion of the camera are radiation <span class="hlt">hardened</span>. They can produce color video with insignificant SNR degradation out to at least 2.85 Mrad of total dose of Co 60 γ-radiation. This represents the first in industry radiation <span class="hlt">hardened</span> color video system, based on a semiconductor photo-detector that has an adequate sensitivity for room light operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009isse.conf..367R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009isse.conf..367R"><span><span class="hlt">Hardened</span> Client Platforms for Secure Internet Banking</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ronchi, C.; Zakhidov, S.</p> <p></p> <p>We review the security of e-banking platforms with particular attention to the exploitable attack vectors of three main attack categories: Man-in-the-Middle, Man-in-the-PC and Man-in-the-Browser. It will be shown that the most serious threats come from combination attacks capable of hacking any transaction without the need to control the authentication process. Using this approach, the security of any authentication system can be bypassed, including those using SecureID Tokens, OTP Tokens, Biometric Sensors and Smart Cards. We will describe and compare two recently proposed e-banking platforms, the ZTIC and the USPD, both of which are based on the use of dedicated client devices, but with diverging approaches with respect to the need of <span class="hlt">hardening</span> the Web client application. It will be shown that the use of a <span class="hlt">Hardened</span> Browser (or H-Browser) component is critical to force attackers to employ complex and expensive techniques and to reduce the strength and variety of social engineering attacks down to physiological fraud levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.V42C1036M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.V42C1036M"><span>Seasonality of <span class="hlt">Volcanic</span> Eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mason, B.; Pyle, D. M.; Dade, W. B.; Jupp, T.</p> <p>2001-12-01</p> <p>An analysis of <span class="hlt">volcanic</span> activity in the last three hundred years reveals that the frequency of onset of <span class="hlt">volcanic</span> eruptions varies systematically with the time of year. We analysed the Smithsonian catalogue of more than 3200 subaerial eruptions recorded during the last 300 years. We also investigated continuous records, which are not part of the general catalogue, of individual explosions at Sakurajima volcano (Japan, 150 events per year since 1955) and Semeru (Indonesia, 100,000 events during the period 1997-2000). A higher proportion (as much as 18 percent of the average monthly rate) of eruptions occur worldwide between December and March. This observation is statistically significant at above the 99 percent level. This pattern is independent of the time interval considered, and emerges whether individual eruptions are counted with equal weight or with weights proportional to event explosivity. Elevated rates of eruption onset in boreal winter months are observed in northern and southern hemispheres alike, as well as in most <span class="hlt">volcanically</span>-active regions including, most prominently, the 'Ring of Fire' surrounding the Pacific basin. Key contributors to this regional pattern include volcanoes in Central and South America, the <span class="hlt">volcanic</span> provinces of the northwest Pacific rim, Indonesia and the southwest Pacific basin. On the smallest spatial scales, some individual volcanoes for which detailed histories exist exhibit peak levels in eruption activity during November-January. Seasonality is attributed to one or more mechanisms associated with the annual hydrological cycle, and may correspond to the smallest time-scale over which fluctuations in stress due to the redistribution of water-masses are felt by the Earth's crust. Our findings have important ramifications for <span class="hlt">volcanic</span> risk assessment, and offer new insight into possible changes in <span class="hlt">volcanic</span> activity during periods of long-term changes in global sea level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....1562M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....1562M"><span>Seasonality of <span class="hlt">volcanic</span> eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mason, B.; Pyle, D.; Dade, B.; Jupp, T.</p> <p>2003-04-01</p> <p>An analysis of <span class="hlt">volcanic</span> activity in the last three hundred years reveals that the frequency of onset of <span class="hlt">volcanic</span> eruptions varies systematically with the time of year. We analysed the Smithsonian catalogue of more than 3200 subaerial eruptions recorded during the last 300 years. We also investigated continuous records, which are not part of the general catalogue, of individual explosions at Sakurajima volcano (Japan, 150 events per year since 1955) and Semeru (Indonesia, 100,000 events during the period 1997-2000). A higher proportion (as much as 18 percent of the average monthly rate) of eruptions occur worldwide between December and March. This observation is statistically significant at above the 99 percent level. This pattern is independent of the time interval considered, and emerges whether individual eruptions are counted with equal weight or with weights proportional to event explosivity. Elevated rates of eruption onset in boreal winter months are observed in northern and southern hemispheres alike, as well as in most <span class="hlt">volcanically</span>-active regions including, most prominently, the 'Ring of Fire' surrounding the Pacific basin. Key contributors to this regional pattern include volcanoes in Central and South America, the <span class="hlt">volcanic</span> provinces of the northwest Pacific rim, Indonesia and the southwest Pacific basin. On the smallest spatial scales, some individual volcanoes for which detailed histories exist exhibit peak levels in eruption activity during November-January. Seasonality is attributed to one or more mechanisms associated with the annual hydrological cycle, and may correspond to the smallest time-scale over which fluctuations in stress due to the redistribution of water-masses are felt by the Earth's crust. Our findings have important ramifications for <span class="hlt">volcanic</span> risk assessment, and offer new insight into possible changes in <span class="hlt">volcanic</span> activity during periods of long-term changes in global sea level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2705511','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2705511"><span>Precambrian Lunar <span class="hlt">Volcanic</span> Protolife</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Green, Jack</p> <p>2009-01-01</p> <p>Five representative terrestrial analogs of lunar craters are detailed relevant to Precambrian fumarolic activity. Fumarolic fluids contain the ingredients for protolife. Energy sources to derive formaldehyde, amino acids and related compounds could be by flow charging, charge separation and <span class="hlt">volcanic</span> shock. With no photodecomposition in shadow, most fumarolic fluids at 40 K would persist over geologically long time periods. Relatively abundant tungsten would permit creation of critical enzymes, Fischer-Tropsch reactions could form polycyclic aromatic hydrocarbons and soluble <span class="hlt">volcanic</span> polyphosphates would enable assembly of nucleic acids. Fumarolic stimuli factors are described. Orbital and lander sensors specific to protolife exploration including combined Raman/laser-induced breakdown spectrocsopy are evaluated. PMID:19582224</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19582224','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19582224"><span>Precambrian lunar <span class="hlt">volcanic</span> protolife.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Green, Jack</p> <p>2009-06-11</p> <p>Five representative terrestrial analogs of lunar craters are detailed relevant to Precambrian fumarolic activity. Fumarolic fluids contain the ingredients for protolife. Energy sources to derive formaldehyde, amino acids and related compounds could be by flow charging, charge separation and <span class="hlt">volcanic</span> shock. With no photodecomposition in shadow, most fumarolic fluids at 40 K would persist over geologically long time periods. Relatively abundant tungsten would permit creation of critical enzymes, Fischer-Tropsch reactions could form polycyclic aromatic hydrocarbons and soluble <span class="hlt">volcanic</span> polyphosphates would enable assembly of nucleic acids. Fumarolic stimuli factors are described. Orbital and lander sensors specific to protolife exploration including combined Raman/laser-induced breakdown spectrocsopy are evaluated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010959','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010959"><span>Mercurian <span class="hlt">volcanism</span> questioned</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wilhelms, D.E.</p> <p>1976-01-01</p> <p>The Mariner 10 television team has argued that extensive plains on Mercury were formed by <span class="hlt">volcanism</span> and compared them with the demonstrably lunar maria. I believe, however, that in stratigraphic relations, surface morphology, and albedo contrast, the Mercurian plains more closely resemble the lunar light plains. These lunar plains were interpreted as <span class="hlt">volcanic</span> on the basis of data comparable to that available to the Mariner 10 investigators but have been shown by the Apollo missions to be of impact origin. The plains on Mercury might also be formed of impact materials, perhaps of impact melt or other basin ejecta that behaved more like a fluid when emplaced that did lunar basin ejecta. ?? 1976.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060036492&hterms=volcanic+hazard&qs=N%3D0%26Ntk%3DTitle%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvolcanic%2Bhazard','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060036492&hterms=volcanic+hazard&qs=N%3D0%26Ntk%3DTitle%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvolcanic%2Bhazard"><span><span class="hlt">Volcanic</span> Hazards Survey in the Trans Mexican <span class="hlt">Volcanic</span> Belt</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abrams, Michael; Siebe, Claus; Macias, Jose Luis</p> <p>1996-01-01</p> <p>We have assembled a digital mosaic of 11 Landsat Thematic images to serve as a mapping base for reconnaissance activities within the Trans Mexican <span class="hlt">Volcanic</span> Belt. This will aid us in interpretation and in the evaluation of potential activity of all the <span class="hlt">volcanic</span> centers there. One result is a <span class="hlt">volcanic</span> hazards map of the area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28270796','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28270796"><span><span class="hlt">Volcanic</span> <span class="hlt">Soils</span> as Sources of Novel CO-Oxidizing Paraburkholderia and Burkholderia: Paraburkholderia hiiakae sp. nov., Paraburkholderia metrosideri sp. nov., Paraburkholderia paradisi sp. nov., Paraburkholderia peleae sp. nov., and Burkholderia alpina sp. nov. a Member of the Burkholderia cepacia Complex.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Weber, Carolyn F; King, Gary M</p> <p>2017-01-01</p> <p>Previous studies showed that members of the Burkholderiales were important in the succession of aerobic, molybdenum-dependent CO oxidizing-bacteria on <span class="hlt">volcanic</span> <span class="hlt">soils</span>. During these studies, four isolates were obtained from Kilauea Volcano (Hawai'i, USA); one strain was isolated from Pico de Orizaba (Mexico) during a separate study. Based on 16S rRNA gene sequence similarities, the Pico de Orizaba isolate and the isolates from Kilauea Volcano were provisionally assigned to the genera Burkholderia and Paraburkholderia, respectively. Each of the isolates possessed a form I coxL gene that encoded the catalytic subunit of carbon monoxide dehydrogenase (CODH); none of the most closely related type strains possessed coxL or oxidized CO. Genome sequences for Paraburkholderia type strains facilitated an analysis of 16S rRNA gene sequence similarities and average nucleotide identities (ANI). ANI did not exceed 95% (the recommended cutoff for species differentiation) for any of the pairwise comparisons among 27 reference strains related to the new isolates. However, since the highest 16S rRNA gene sequence similarity among this set of reference strains was 98.93%, DNA-DNA hybridizations (DDH) were performed for two isolates whose 16S rRNA gene sequence similarities with their nearest phylogenetic neighbors were 98.96 and 99.11%. In both cases DDH values were <16%. Based on multiple variables, four of the isolates represent novel species within the Paraburkholderia: Paraburkholderia hiiakae sp. nov. (type strain I2(T) = DSM 28029(T) = LMG 27952(T)); Paraburkholderia paradisi sp. nov. (type strain WA(T) = DSM 28027(T) = LMG 27949(T)); Paraburkholderia peleae sp. nov. (type strain PP52-1(T) = DSM 28028(T) = LMG 27950(T)); and Paraburkholderia metrosideri sp. nov. (type strain DNBP6-1(T) = DSM 28030(T) = LMG 28140(T)). The remaining isolate represents the first CO-oxidizing member of the Burkholderia cepacia complex: Burkholderia alpina sp. nov. (type strain PO-04-17-38(T) = DSM</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5318905','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5318905"><span><span class="hlt">Volcanic</span> <span class="hlt">Soils</span> as Sources of Novel CO-Oxidizing Paraburkholderia and Burkholderia: Paraburkholderia hiiakae sp. nov., Paraburkholderia metrosideri sp. nov., Paraburkholderia paradisi sp. nov., Paraburkholderia peleae sp. nov., and Burkholderia alpina sp. nov. a Member of the Burkholderia cepacia Complex</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Weber, Carolyn F.; King, Gary M.</p> <p>2017-01-01</p> <p>Previous studies showed that members of the Burkholderiales were important in the succession of aerobic, molybdenum-dependent CO oxidizing-bacteria on <span class="hlt">volcanic</span> <span class="hlt">soils</span>. During these studies, four isolates were obtained from Kilauea Volcano (Hawai‘i, USA); one strain was isolated from Pico de Orizaba (Mexico) during a separate study. Based on 16S rRNA gene sequence similarities, the Pico de Orizaba isolate and the isolates from Kilauea Volcano were provisionally assigned to the genera Burkholderia and Paraburkholderia, respectively. Each of the isolates possessed a form I coxL gene that encoded the catalytic subunit of carbon monoxide dehydrogenase (CODH); none of the most closely related type strains possessed coxL or oxidized CO. Genome sequences for Paraburkholderia type strains facilitated an analysis of 16S rRNA gene sequence similarities and average nucleotide identities (ANI). ANI did not exceed 95% (the recommended cutoff for species differentiation) for any of the pairwise comparisons among 27 reference strains related to the new isolates. However, since the highest 16S rRNA gene sequence similarity among this set of reference strains was 98.93%, DNA-DNA hybridizations (DDH) were performed for two isolates whose 16S rRNA gene sequence similarities with their nearest phylogenetic neighbors were 98.96 and 99.11%. In both cases DDH values were <16%. Based on multiple variables, four of the isolates represent novel species within the Paraburkholderia: Paraburkholderia hiiakae sp. nov. (type strain I2T = DSM 28029T = LMG 27952T); Paraburkholderia paradisi sp. nov. (type strain WAT = DSM 28027T = LMG 27949T); Paraburkholderia peleae sp. nov. (type strain PP52-1T = DSM 28028T = LMG 27950T); and Paraburkholderia metrosideri sp. nov. (type strain DNBP6-1T = DSM 28030T = LMG 28140T). The remaining isolate represents the first CO-oxidizing member of the Burkholderia cepacia complex: Burkholderia alpina sp. nov. (type strain PO-04-17-38T = DSM 28031T = LMG 28138T</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5988028','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5988028"><span>Radiation-<span class="hlt">hardened</span> 16K-bit MNOS EAROM</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Knoll, M.G.; Dellin, T.A.; Jones, R.V.</p> <p>1983-01-01</p> <p>A radiation-<span class="hlt">hardened</span> silicon-gate CMOS/NMNOS 16K-bit EAROM has been designed, fabricated, and evaluated. This memory has been designed to be used as a ROM replacement in radiation-<span class="hlt">hardened</span> microprocessor-based systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090008516','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090008516"><span>Radiation-<span class="hlt">Hardened</span> Electronics for Space Environments (RHESE)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keys, Andrew S.; Adams, James H.; Patrick, Marshall C.; Johnson, Michael; Cressler, John D.</p> <p>2008-01-01</p> <p>This conference poster explores NASA's Radiation-<span class="hlt">Hardened</span> Electronics for Space Environments project. This project aims to advance the state of the art in high performance, radiation-<span class="hlt">hardened</span> electronics that enable the long-term, reliable operation of a spacecraft in extreme radiation and temperature of space and the lunar surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MSHT...55..157M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MSHT...55..157M"><span>Certification of <span class="hlt">hardened</span> surface layers by magnetic and electromagnetic methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitropol'skaya, S. Yu.</p> <p>2013-07-01</p> <p>The possibilities of certification of <span class="hlt">hardened</span> surface layers by measurement of coercive force, eddy current inspection and analysis of the field dependence of differential magnetic permeability μ d ( H) are considered. The advantages of analysis of the pattern of peaks on the μ d ( H) dependence for estimating the state of surface-<span class="hlt">hardened</span> steels subjected to subsequent force loading are shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070020429','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070020429"><span>Radiation-<span class="hlt">Hardened</span> Electronics for the Space Environment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keys, Andrew S.; Watson, Michael D.</p> <p>2007-01-01</p> <p>RHESE covers a broad range of technology areas and products. - Radiation <span class="hlt">Hardened</span> Electronics - High Performance Processing - Reconfigurable Computing - Radiation Environmental Effects Modeling - Low Temperature Radiation <span class="hlt">Hardened</span> Electronics. RHESE has aligned with currently defined customer needs. RHESE is leveraging/advancing SOA space electronics, not duplicating. - Awareness of radiation-related activities through out government and industry allow advancement rather than duplication of capabilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19260908','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19260908"><span>The <span class="hlt">hardening</span> phenomenon in irritant contact dermatitis: an interpretative update.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Watkins, Shannon A; Maibach, Howard I</p> <p>2009-03-01</p> <p>Irritant contact dermatitis (ICD) is common and poses a significant problem in high-risk populations. In most cases, ICD resolves despite continued exposure in a process known as '<span class="hlt">hardening</span>', allowing individuals to continue with their work. Those who cannot clear ICD develop chronic ICD, which is a significant source of emotional, physical, and financial distress for affected individuals. While <span class="hlt">hardening</span> is well known among labourers and clinicians, its mechanism remains to be elucidated. Much can be learned from the study of self-healing processes like the <span class="hlt">hardening</span> phenomenon. This overview briefly documents the pathogenesis of ICD, focuses on the latest advances pertaining to the <span class="hlt">hardening</span> phenomenon in ICD, and then highlights potential avenues of productive research. A better understanding of the '<span class="hlt">hardening</span>' process in the skin will hopefully lead to advances for the treatment of ICD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26609685','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26609685"><span>New analytical approach for neutron beam-<span class="hlt">hardening</span> correction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hachouf, N; Kharfi, F; Hachouf, M; Boucenna, A</p> <p>2016-01-01</p> <p>In neutron imaging, the beam-<span class="hlt">hardening</span> effect has a significant effect on quantitative and qualitative image interpretation. This study aims to propose a linearization method for beam-<span class="hlt">hardening</span> correction. The proposed method is based on a new analytical approach establishing the attenuation coefficient as a function of neutron energy. Spectrum energy shift due to beam <span class="hlt">hardening</span> is studied on the basis of Monte Carlo N-Particle (MCNP) simulated data and the analytical data. Good agreement between MCNP and analytical values has been found. Indeed, the beam-<span class="hlt">hardening</span> effect is well supported in the proposed method. A correction procedure is developed to correct the errors of beam-<span class="hlt">hardening</span> effect in neutron transmission, and therefore for projection data correction. The effectiveness of this procedure is determined by its application in correcting reconstructed images.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=North+AND+American+AND+plate&id=EJ394260','ERIC'); return false;" href="http://eric.ed.gov/?q=North+AND+American+AND+plate&id=EJ394260"><span><span class="hlt">Volcanism</span> at Rifts.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>White, Robert S.; McKenzie, Dan P.</p> <p>1989-01-01</p> <p>Investigates the nature of catastrophic <span class="hlt">volcanism</span> and the rifting process. Describes two kinds of evidence: quantitative descriptions of rock melting and a wide range of observations. Discusses examples of continent growth in the North Atlantic, India and the Seychelles islands, and the South Atlantic. (YP)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=volcano&pg=2&id=EJ480122','ERIC'); return false;" href="http://eric.ed.gov/?q=volcano&pg=2&id=EJ480122"><span><span class="hlt">Volcanism</span> in the Classroom.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Albin, Edward F.</p> <p>1993-01-01</p> <p>Presents activities to familiarize junior high school students with the processes behind and reasons for <span class="hlt">volcanism</span>, which is generally a planet's way of releasing excessive internal heat and pressure. Students participate in the creation of four important volcano-related simulations: a lava flow, a shield volcano, a cinder-cone volcano, and a…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5730026','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5730026"><span>Precipitation <span class="hlt">hardening</span> in 350 grade maraging steel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Viswanathan, U.K. . Radiometallurgy Div.); Dey, G.K. . Metallurgy Division); Asundi, M.K. )</p> <p>1993-11-01</p> <p>Evolution of microstructure in 350 grade commercial maraging steel has been examined. In the earlier stages of aging, the strengthening phases are formed by the heterogeneous precipitation, and these phases have been identified as intermetallic compounds of the Ni[sub 3] (Ti, Mo) and Fe[sub 2]Mo types. The kinetics of precipitation are studied in terms of the activation energy by carrying out isothermal hardness measurements of aged material. The mechanical properties in the peak-aged and overaged conditions were evaluated and the flow behavior examined. The overaging behavior of the steel has been studied and the formation of austenite of different morphologies identified. The crystallography of the austenite has been examined in detail. From the microstructural examination of peak-aged and deformed samples, it could be inferred that the dislocation-precipitate interaction is by precipitate shearing. Increased work <span class="hlt">hardening</span> of the material in the overaged condition was suggestive of looping of precipitates by dislocations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009hrb..book..329B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009hrb..book..329B"><span>Keystroke Dynamics-Based Credential <span class="hlt">Hardening</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bartlow, Nick; Cukic, Bojan</p> <p></p> <p>abstract Keystroke dynamics are becoming a well-known method for strengthening username- and password-based credential sets. The familiarity and ease of use of these traditional authentication schemes combined with the increased trustworthiness associated with biometrics makes them prime candidates for application in many web-based scenarios. Our keystroke dynamics system uses Breiman’s random forests algorithm to classify keystroke input sequences as genuine or imposter. The system is capable of operating at various points on a traditional ROC curve depending on application-specific security needs. As a username/password authentication scheme, our approach decreases the system penetration rate associated with compromised passwords up to 99.15%. Beyond presenting results demonstrating the credential <span class="hlt">hardening</span> effect of our scheme, we look into the notion that a user’s familiarity to components of a credential set can non-trivially impact error rates.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780011567','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780011567"><span>Jerky loads on surface-<span class="hlt">hardened</span> gears</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rettig, H.; Wirth, X.</p> <p>1978-01-01</p> <p>Damage occurs again and again in practice in the form of transmissions with surface <span class="hlt">hardened</span> gears which break after a very long operating time (explained by seldom occurring jerky loads). Gear drives are frequently exposed to jerky stresses which are greater than their fatigue limit. These stresses are considered in gear calculations, first, by shock factors when the transmission is to be designed as high endurance with regard to overloads and, second, in the form of operating ratios when the design is to be time enduring with regard to overloads. The size of the operating ratio depends not only on torque characteristics, drive and processing machine, but also on the material and heat treatment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.P13B1387B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.P13B1387B"><span>The Zuni-Bandera <span class="hlt">Volcanic</span> Field, NM: An Analog for Exploring Planetary <span class="hlt">Volcanic</span> Terrains</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bleacher, J. E.; Garry, W. B.; Zimbelman, J. R.; Crumpler, L. S.; Aubele, J. C.</p> <p>2010-12-01</p> <p>The Zuni-Bandera <span class="hlt">volcanic</span> field, near Grants, New Mexico, is comprised of <span class="hlt">volcanic</span> deposits from several basaltic eruptions during the last million years. This vent field exhibits a diverse group of coalesced lava flows and displays well-preserved <span class="hlt">volcanic</span> features including a’a and pahoehoe flows, collapsed lava tubes, cinder cones and low shields. The McCartys flow is a 48-km long inflated basalt flow and is the youngest in the field at around 3000 years old. Over the last three years we have used the Zuni-Bandera <span class="hlt">volcanic</span> field, and the McCartys flow in particular, as a terrestrial analog for exploring planetary <span class="hlt">volcanic</span> fields, and understanding the role of lava sheet inflation in flow field development. We have conducted three different styles of analog tests, 1) basic field science focused on understanding lava sheet inflation, 2) mission operations tests related to EVA design and real-time modification of traverse plans, and 3) science enabling technology tests. The Zuni-Bandera field is an ideal location for each style of analog test because it provides easy access to a diverse set of <span class="hlt">volcanic</span> features with variable quality of preservation. However, many limitations must also be considered in order to maximize lessons learned. The McCartys flow displays well-preserved inflation plateaus that rise up to 15 m above the surrounding field. The preservation state enables textures and morphologies indicative of this process to be characterized. However, the pristine nature of the flow does not compare well with the much older and heavily modified inflated flows of Mars and the Moon. Older flows west of McCartys add value to this aspect of analog work because of their degraded surfaces, development of <span class="hlt">soil</span> horizons, loose float, and limited exposure of outcrops, similar to what might be observed on the Moon or Mars. EVA design tests and science enabling technology tests at the Zuni-Bandera field provide the opportunity to document and interpret the relationships</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AcMSn.tmp...67K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AcMSn.tmp...67K"><span>Finite deformation analysis of crack tip fields in plastically compressible <span class="hlt">hardening-softening-hardening</span> solids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khan, D.; Singh, S.; Needleman, A.</p> <p>2016-11-01</p> <p>Crack tip fields are calculated under plane strain small scale yielding conditions. The material is characterized by a finite strain elastic-viscoplastic constitutive relation with various <span class="hlt">hardening-softening-hardening</span> hardness functions. Both plastically compressible and plastically incompressible solids are considered. Displacements corresponding to the isotropic linear elastic mode I crack field are prescribed on a remote boundary. The initial crack is taken to be a semi-circular notch and symmetry about the crack plane is imposed. Plastic compressibility is found to give an increased crack opening displacement for a given value of the applied loading. The plastic zone size and shape are found to depend on the plastic compressibility, but not much on whether material softening occurs near the crack tip. On the other hand, the near crack tip stress and deformation fields depend sensitively on whether or not material softening occurs. The combination of plastic compressibility and softening (or softening-<span class="hlt">hardening</span>) has a particularly strong effect on the near crack tip stress and deformation fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AcMSn..33..148K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AcMSn..33..148K"><span>Finite deformation analysis of crack tip fields in plastically compressible <span class="hlt">hardening-softening-hardening</span> solids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khan, D.; Singh, S.; Needleman, A.</p> <p>2017-02-01</p> <p>Crack tip fields are calculated under plane strain small scale yielding conditions. The material is characterized by a finite strain elastic-viscoplastic constitutive relation with various <span class="hlt">hardening-softening-hardening</span> hardness functions. Both plastically compressible and plastically incompressible solids are considered. Displacements corresponding to the isotropic linear elastic mode I crack field are prescribed on a remote boundary. The initial crack is taken to be a semi-circular notch and symmetry about the crack plane is imposed. Plastic compressibility is found to give an increased crack opening displacement for a given value of the applied loading. The plastic zone size and shape are found to depend on the plastic compressibility, but not much on whether material softening occurs near the crack tip. On the other hand, the near crack tip stress and deformation fields depend sensitively on whether or not material softening occurs. The combination of plastic compressibility and softening (or softening-<span class="hlt">hardening</span>) has a particularly strong effect on the near crack tip stress and deformation fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.V23A1243R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.V23A1243R"><span><span class="hlt">Volcanic</span> CO2 as a major agent of weathering in <span class="hlt">volcanic</span> regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rive, K.; Gaillardet, J.; Agrinier, P.; Rad, S.</p> <p>2007-12-01</p> <p>According to high erosion rates, weathering of <span class="hlt">volcanic</span> areas is one of the main processes controlling the atmospheric CO2 levels (e.g. Louvat, 1997, Dessert et al., 2003). So far, the origin of CO2 was assumed to be mainly atmospheric. The origin and consumption rates of CO2 can be estimated using concentration of Dissolved Inorganic Carbon (DIC ~ bicarbonates) in the rivers and carbon stable isotopes. The processes governing the CO2 consumption by chemical weathering were studied in four <span class="hlt">volcanic</span> areas, with climates from tropical to sub-polar, in different geodynamic contexts. Lesser Antilles, Reunion, Iceland and French Massif Central are ideal sites for the study of weathering due to the gradients of rainfall (up to 14m/yr), rock ages (tertiary to subactual) and <span class="hlt">volcanic</span> activities, inducing variable weathering rates (50- 400t/km\\2/yr). δ13CDIC and major elements chemistry were studied in streams, springs and <span class="hlt">soil</span> solutions of these four areas. The δ13CDIC and major elements concentrations are highly variable, and allow us to identify the origin of DIC as a mixing between biogenic CO2 (average value of δ13C ~ - 29.1±2.0‰ in tropical areas, -26‰ in temperate to sub-polar climate) and <span class="hlt">volcanic</span> CO2 (δ13CDIC = -5 to 3‰). We found that <span class="hlt">volcanic</span> CO2 is a major source of carbon, the highest contribution being for zones with high infiltration of water (up to 100\\percent of DIC for Piton de la Fournaise in Reunion). As inferred by Rad et al. (2007) from major elements, this isotopic study of the DIC cycling in the river demonstrates the importance of the <span class="hlt">volcanic</span> fluids on chemical weathering processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/145329','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/145329"><span>1992-93 Results of geomorphological and field studies <span class="hlt">Volcanic</span> Studies Program, Yucca Mountain Project</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wells, S.G.</p> <p>1993-10-01</p> <p>Field mapping and stratigraphic studies were completed of the Black Tank <span class="hlt">volcanic</span> center, which represents the southwestern most eruptive center in the Cima <span class="hlt">volcanic</span> field of California. The results of this mapping are presented. Contacts between <span class="hlt">volcanic</span> units and geomorphic features were field checked, incorporating data from eight field trenches as well as several exposures along Black Tank Wash. Within each of the eight trenches, logs were measured and stratigraphic sections were described. These data indicate that three, temporally separate <span class="hlt">volcanic</span> eruptions occurred at the Black Tank center. The field evidence for significant time breaks between each stratigraphic unit is the presence of <span class="hlt">soil</span> and pavement-bounded unconformities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22947486','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22947486"><span>Porosity and mechanically optimized PLGA based in situ <span class="hlt">hardening</span> systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schloegl, W; Marschall, V; Witting, M Y; Volkmer, E; Drosse, I; Leicht, U; Schieker, M; Wiggenhorn, M; Schaubhut, F; Zahler, S; Friess, W</p> <p>2012-11-01</p> <p>Goal of the present study was to develop and to characterize in situ-<span class="hlt">hardening</span>, porous PLGA-based systems for their future application as bone grafting materials. Therefore, we investigated the precipitation behavior of formulations containing PLGA and a water-miscible solvent, DMSO, PEG 400, and NMP. To increase porosity, a pore forming agent (NaCMC) was added and to enhance mechanical properties of the system, an inorganic filler (α-TCP) was incorporated. The behavior upon contact with water and the influence of the prior addition of aqueous media on the morphology of the corresponding <span class="hlt">hardened</span> implants were investigated. We proved cell-compatibility by live/dead assays for the <span class="hlt">hardened</span> porous polymer/ceramic-composite scaffolds. The IsHS formulations can therefore be used to manufacture <span class="hlt">hardened</span> scaffolds ex vivo by using molds with the desired shape and size. Cells were further successfully incorporated into the IsHS by precultivating the cells on the α-TCP-powder prior to their admixing to the formulation. However, cell viability could not be maintained due to toxicity of the tested solvents. But, the results demonstrate that in vivo cells should well penetrate, adhere, and proliferate in the <span class="hlt">hardened</span> scaffolds. Consequently, we consider the in situ <span class="hlt">hardening</span> system being an excellent candidate as a filling material for non-weight-bearing orthopedic indications, as the resulting properties of the <span class="hlt">hardened</span> implant fulfill indication-specific needs like mechanical stability, elasticity, and porosity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011CompM..48..631B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011CompM..48..631B"><span>An extended crystal plasticity model for latent <span class="hlt">hardening</span> in polycrystals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bargmann, Swantje; Svendsen, Bob; Ekh, Magnus</p> <p>2011-12-01</p> <p>In this contribution, a computational approach to modeling size-dependent self- and latent <span class="hlt">hardening</span> in polycrystals is presented. Latent <span class="hlt">hardening</span> is the <span class="hlt">hardening</span> of inactive slip systems due to active slip systems. We focus attention on the investigation of glide system interaction, latent <span class="hlt">hardening</span> and excess dislocation development. In particular, latent <span class="hlt">hardening</span> results in a transition to patchy slip as a first indication and expression of the development of dislocation microstructures. To this end, following Nye (Acta Metall 1:153-162, 1953), Kondo (in Proceedings of the second Japan national congress for applied mechanics. Science Council of Japan, Tokyo, pp. 41-47, 1953), and many others, local deformation incompatibility in the material is adopted as a measure of the density of geometrically necessary dislocations. Their development results in additional energy being stored in the material, leading to additional kinematic-like <span class="hlt">hardening</span> effects. A large-deformation model for latent <span class="hlt">hardening</span> is introduced. This approach is based on direct exploitation of the dissipation principle to derive all field relations and (sufficient) forms of the constitutive relations as based on the free energy density and dissipation potential. The numerical implementation is done via a dual-mixed finite element method. A numerical example for polycrystals is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EOSTr..94...72P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EOSTr..94...72P"><span>Exploring Hawaiian <span class="hlt">Volcanism</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poland, Michael P.; Okubo, Paul G.; Hon, Ken</p> <p>2013-02-01</p> <p>In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the <span class="hlt">volcanic</span> disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai`i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and <span class="hlt">volcanic</span> hazards. In the 100 years since HVO's founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists' understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70046813','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70046813"><span>Exploring Hawaiian <span class="hlt">volcanism</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Poland, Michael P.; Okubo, Paul G.; Hon, Ken</p> <p>2013-01-01</p> <p>In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the <span class="hlt">volcanic</span> disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai‘i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and <span class="hlt">volcanic</span> hazards. In the 100 years since HVO’s founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists’ understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910012328','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910012328"><span><span class="hlt">Volcanism</span>-Climate Interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Walter, Louis S. (Editor); Desilva, Shanaka (Editor)</p> <p>1991-01-01</p> <p>The range of disciplines in the study of <span class="hlt">volcanism</span>-climate interactions includes paleoclimate, volcanology, petrology, tectonics, cloud physics and chemistry, and climate and radiation modeling. Questions encountered in understanding the interactions include: the source and evolution of sulfur and sulfur-gaseous species in magmas; their entrainment in <span class="hlt">volcanic</span> plumes and injection into the stratosphere; their dissipation rates; and their radiative effects. Other issues include modeling and measuring regional and global effects of such large, dense clouds. A broad-range plan of research designed to answer these questions was defined. The plan includes observations of volcanoes, rocks, trees, and ice cores, as well as satellite and aircraft observations of erupting volcanoes and resulting lumes and clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015120','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015120"><span>California's potential <span class="hlt">volcanic</span> hazards</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Jorgenson, P.</p> <p>1989-01-01</p> <p>This is a summary of "Potential Hazards from Future <span class="hlt">Volcanic</span> Eruptions in California' (USGS Bulletin No. 1847: price $4.75). The chief areas of danger are Lassen Peak, Mount Shasta and Medicine Lake Highland in the north; Clear Lake, Mono Lake and Long Valley in the centre; and Owen's River-Death Valley, Amboy Crater and the Saltan Butter in the south of the State. -A.Scarth</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910012333','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910012333"><span><span class="hlt">Volcanic</span> effects on climate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Robock, Alan</p> <p>1991-01-01</p> <p><span class="hlt">Volcanic</span> eruptions which inject large amounts of sulfur-rich gas into the stratosphere produce dust veils which last years and cool the earth's surface. At the same time, these dust veils absorb enough solar radiation to warm the stratosphere. Since these temperature changes at the earth's surface and in the stratosphere are both in the opposite direction of hypothesized effects from greenhouse gases, they act to delay and mask the detection of greenhouse effects on the climate system. Tantalizing recent research results have suggested regional effects of <span class="hlt">volcanic</span> eruptions, including effects on El Nino/Southern Oscillation (ENSO). In addition, a large portion of the global climate change of the past 100 years may be due to the effects of volcanoes, but a definite answer is not yet clear. While effects of several years were demonstrated with both data studies and numerical models, long-term effects, while found in climate model calculations, await confirmation with more realistic models. Extremely large explosive prehistoric eruptions may have produced severe weather and climate effects, sometimes called a '<span class="hlt">volcanic</span> winter'. Complete understanding of the above effects of volcanoes is hampered by inadequacies of data sets on <span class="hlt">volcanic</span> dust veils and on climate change. Space observations can play an increasingly important role in an observing program in the future. The effects of volcanoes are not adequately separated from ENSO events, and climate modeling of the effects of volcanoes is in its infancy. Specific suggestions are made for future work to improve the knowledge of this important component of the climate system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992EOSTr..73...42B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992EOSTr..73...42B"><span><span class="hlt">Volcanic</span> alert in antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bush, Susan</p> <p>1992-01-01</p> <p>On January 14, members of the Council of Managers of National Antarctic Programs (COMNAP) were alerted to possible <span class="hlt">volcanic</span> activity on Deception Island, Antarctica. The island, located at latitude 62%57‧S, longitude 60'40‧W, attracts many tourists.COMNAP is a group of national program managers of 25 countries that have government programs in the Antarctic. Its function is to implement measures adopted by the Antarctic Treaty parties, including fostering international cooperation in scientific research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011psrd.reptE.155M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011psrd.reptE.155M"><span>Timeline of Martian <span class="hlt">Volcanism</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martel, L. M. V.</p> <p>2011-05-01</p> <p>A recent study of Martian <span class="hlt">volcanism</span> presents a timeline of the last major eruptions from 20 large volcanoes, based on the relative ages of caldera surfaces determined by crater counting. Stuart Robbins, Gaetano Di Achille, and Brian Hynek (University of Colorado) counted craters on high-resolution images from the the Context Camera (CTX) on Mars Reconnaissance Orbiter to date individual calderas, or terraces within calderas, on the 20 major Martian volcanoes. Based on their timeline and mapping, rates and durations of eruptions and transitions from explosive to effusive activity varied from volcano to volcano. The work confirms previous findings by others that <span class="hlt">volcanism</span> was continuous throughout Martian geologic history until about one to two hundred million years ago, the final <span class="hlt">volcanic</span> events were not synchronous across the planet, and the latest large-scale caldera activity ended about 150 million years ago in the Tharsis province. This timing correlates well with the crystallization ages (~165-170 million years) determined for the youngest basaltic Martian meteorites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/45998','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/45998"><span>Cylindrical shell buckling through strain <span class="hlt">hardening</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bandyopadhyay, K.; Xu, J.; Shteyngart, S.; Gupta, D.</p> <p>1995-04-01</p> <p>Recently, the authors published results of plastic buckling analysis of cylindrical shells. Ideal elastic-plastic material behavior was used for the analysis. Subsequently, the buckling analysis program was continued with the realistic stress-strain relationship of a stainless steel alloy which does not exhibit a clear yield point. The plastic buckling analysis was carried out through the initial stages of strain <span class="hlt">hardening</span> for various internal pressure values. The computer program BOSOR5 was used for this purpose. Results were compared with those obtained from the idealized elastic-plastic relationship using the offset stress level at 0.2% strain as the yield stress. For moderate hoop stress values, the realistic stress-grain case shows a slight reduction of the buckling strength. But, a substantial gain in the buckling strength is observed as the hoop stress approaches the yield strength. Most importantly, the shell retains a residual strength to carry a small amount of axial compressive load even when the hoop stress has exceeded the offset yield strength.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SPIE.8408E..03D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SPIE.8408E..03D"><span>Cyber situational awareness and differential <span class="hlt">hardening</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dwivedi, Anurag; Tebben, Dan</p> <p>2012-06-01</p> <p>The advent of cyber threats has created a need for a new network planning, design, architecture, operations, control, situational awareness, management, and maintenance paradigms. Primary considerations include the ability to assess cyber attack resiliency of the network, and rapidly detect, isolate, and operate during deliberate simultaneous attacks against the network nodes and links. Legacy network planning relied on automatic protection of a network in the event of a single fault or a very few simultaneous faults in mesh networks, but in the future it must be augmented to include improved network resiliency and vulnerability awareness to cyber attacks. Ability to design a resilient network requires the development of methods to define, and quantify the network resiliency to attacks, and to be able to develop new optimization strategies for maintaining operations in the midst of these newly emerging cyber threats. Ways to quantify resiliency, and its use in visualizing cyber vulnerability awareness and in identifying node or link criticality, are presented in the current work, as well as a methodology of differential network <span class="hlt">hardening</span> based on the criticality profile of cyber network components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/4127770','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/4127770"><span>Weldable, age <span class="hlt">hardenable</span>, austenitic stainless steel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Brooks, J.A.; Krenzer, R.W.</p> <p>1975-07-22</p> <p>An age <span class="hlt">hardenable</span>, austenitic stainless steel having superior weldability properties as well as resistance to degradation of properties in a hydrogen atmosphere is described. It has a composition of from about 24.0 to about 34.0 weight percent (w/o) nickel, from about 13.5 to about 16.0 w/o chromium, from about 1.9 to about 2.3 w/o titanium, from about 1.0 to about 1.5 w/ o molybdenum, from about 0.01 to about 0.05 w/o carbon, from about 0 to about 0.25 w/o manganese, from about 0 to about 0.01 w/o phosphorous and preferably about 0.005 w/o maximum, from about 0 to about 0.010 w/o sulfur and preferably about 0.005 w/o maximum, from about 0 to about 0.25 w/o silicon, from about 0.1 to about 0.35 w/o aluminum, from about 0.10 to about 0.50 w/o vanadium, from about 0 to about 0.0015 w/o boron, and the balance essentially iron. (auth)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990STIN...9025260F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990STIN...9025260F"><span>Design concepts for <span class="hlt">hardened</span> communications structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Flathau, William J.; Smith, William G.</p> <p>1990-03-01</p> <p>An important component of any <span class="hlt">hardened</span> command and control structure is the antenna system that provides communication with the outside world. Two types of antennae were considered; i.e., the whip type and the directional. The whip type is for short range communication and the directional is for use primarily with satellites. In the super high frequency range, the use of directional antennae having parabolic dishes greater than 8 feet in diameter are common. In the very extra high frequency range, dishes that are 2 to 3 feet in diameter are used. The whip type antenna should extend up to, say, 60 feet in the air. Based on this background, a family of structures was designed that can protect whip and directional antennae from the blast and shock effects from a 1-MT device for ground surface overpressure ranging from 15,000 to 500 psi. As the antennae, transmitters, receivers, power supplies, and lifting mechanisms will be located within such structures, appropriate shock spectra plots were developed to determine if the fragility level of pertinent equipment will be exceeded and for use in designing shock isolation systems. Button up periods of 1 and 4 weeks were considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160012369','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160012369"><span>Open Source Radiation <span class="hlt">Hardened</span> by Design Technology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shuler, Robert</p> <p>2016-01-01</p> <p>The proposed technology allows use of the latest microcircuit technology with lowest power and fastest speed, with minimal delay and engineering costs, through new Radiation <span class="hlt">Hardened</span> by Design (RHBD) techniques that do not require extensive process characterization, technique evaluation and re-design at each Moore's Law generation. The separation of critical node groups is explicitly parameterized so it can be increased as microcircuit technologies shrink. The technology will be open access to radiation tolerant circuit vendors. INNOVATION: This technology would enhance computation intensive applications such as autonomy, robotics, advanced sensor and tracking processes, as well as low power applications such as wireless sensor networks. OUTCOME / RESULTS: 1) Simulation analysis indicates feasibility. 2)Compact voting latch 65 nanometer test chip designed and submitted for fabrication -7/2016. INFUSION FOR SPACE / EARTH: This technology may be used in any digital integrated circuit in which a high level of resistance to Single Event Upsets is desired, and has the greatest benefit outside low earth orbit where cosmic rays are numerous.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/203774','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/203774"><span>Radiation-induced segregation, <span class="hlt">hardening</span>, and IASCC</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Eason, E.D.; Nelson, E.E.</p> <p>1995-12-31</p> <p>Intergranular cracking has been discovered after extended radiation exposure in several boiling water reactor (BWR) internal components made of austenitic stainless steel and nickel-based alloys. There are fewer field observations of intergranular cracking in pressurized water reactors (PWR), but failures have occurred in bolts, springs, and fuel cladding. There is concern for other PWR components, some of which will receive greater radiation doses than BWR components during the plant lifetime. This paper presents the results of an investigation on the connection between radiation induced segregation, <span class="hlt">hardening</span> and irradiation-assisted stress corrosion cracking (IASCC). A data base was developed containing the available data on austenitic stainless steel where the grain boundary composition was measured by Field Emission Gun-Scanning Transmission Election Microscopy (FEG-STEM), the stress corrosion susceptibility was measured by constant extension rate tests (CERT) in light water reactor environments, some estimate of irradiated strength was available and the irradiation was conducted in a power reactor. The data base was analyzed using advanced data analysis techniques, including tree-structured pattern recognition and transformation analysis codes. The most sensitive variables and optimal modeling forms were identified using these techniques, then preliminary models were calibrated using nonlinear least squares. The results suggest that more than one mechanism causes IASCC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6835380','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6835380"><span>Radiation-<span class="hlt">hardened</span> microwave communications system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smith, S.F.; Crutcher, R.I.; Vandermolen, R.I. )</p> <p>1990-01-01</p> <p>The consolidated fuel reprocessing program (CFRP) at the Oak Ridge National Laboratory (ORNL) has been developing signal transmission techniques and equipment to improve the efficiency of remote handling operations for nuclear applications. These efforts have been largely directed toward the goals of (a) remotely controlling bilateral force-reflecting servomanipulators for dexterous manipulation-based operations in remote maintenance tasks and (b) providing television viewing of the work site. In September 1987, developmental microwave transceiving hardware operating with dish antennas was demonstrated in the advanced integrated maintenance system (AIMS) facility at ORNL, successfully implementing both high-quality one-way television transmissions and simultaneous bidirectional digital control data transmissions with very low error rates. Initial test results based on digital transmission at a 1.0-Mbaud data rate indicated that the error rates of the microwave system were comparable to those of a hardwired system. During these test intervals, complex manipulator operations were performed, and the AIMS transporter was moved repeatedly without adverse effects on data integrity. Results of these tests have been factored into subsequent phases of the development program, with an ultimate goal of designing a fully radiation-<span class="hlt">hardened</span> microwave signal transmission system for use in nuclear facilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8171109','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8171109"><span>Work <span class="hlt">hardening</span> and work conditioning interventions: do they affect disability?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lechner, D E</p> <p>1994-05-01</p> <p>The purpose of this article is to review the research on the effectiveness of work <span class="hlt">hardening</span> and work conditioning programs. Twelve studies of work <span class="hlt">hardening</span> and work conditioning programs in the United States and abroad were reviewed. One study produced convincing evidence in a randomized study that a work conditioning program was useful in producing a higher percentage of return to work and an earlier return to work in a group of patients off work for at least 2 months. Another study demonstrated that a work <span class="hlt">hardening</span> program increased the rate of return to work by 52% in patients off work for greater than 4 months. Most of the other studies reviewed suggested positive results, but more carefully documented, randomized, and controlled studies are needed to support the efficacy of these programs and to determine the optimum and most cost-effective work <span class="hlt">hardening</span> and work conditioning interventions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19690000407','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19690000407"><span>Possible correlation between work-<span class="hlt">hardening</span> and fatigue-failure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kettunen, P. O.; Kocks, U. F.</p> <p>1969-01-01</p> <p>Conceptual theory proposes that cyclic <span class="hlt">hardening</span> due to non-uniform strain and stress amplitudes during testing, especially during the initial application of stress to a specimen, may correlate positively with the ultimate strength of the specimen under test.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27009239','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27009239"><span>Microscopic Origin of Strain <span class="hlt">Hardening</span> in Methane Hydrate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jia, Jihui; Liang, Yunfeng; Tsuji, Takeshi; Murata, Sumihiko; Matsuoka, Toshifumi</p> <p>2016-03-24</p> <p>It has been reported for a long time that methane hydrate presents strain <span class="hlt">hardening</span>, whereas the strength of normal ice weakens with increasing strain after an ultimate strength. However, the microscopic origin of these differences is not known. Here, we investigated the mechanical characteristics of methane hydrate and normal ice by compressive deformation test using molecular dynamics simulations. It is shown that methane hydrate exhibits strain <span class="hlt">hardening</span> only if the hydrate is confined to a certain finite cross-sectional area that is normal to the compression direction. For normal ice, it does not present strain <span class="hlt">hardening</span> under the same conditions. We show that hydrate guest methane molecules exhibit no long-distance diffusion when confined to a finite-size area. They appear to serve as non-deformable units that prevent hydrate structure failure, and thus are responsible for the strain-<span class="hlt">hardening</span> phenomenon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19700000134','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19700000134"><span>Stress corrosion cracking evaluation of precipitation-<span class="hlt">hardening</span> stainless steel</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Humphries, T. S.; Nelson, E. E.</p> <p>1970-01-01</p> <p>Accelerated test program results show which precipitation <span class="hlt">hardening</span> stainless steels are resistant to stress corrosion cracking. In certain cases stress corrosion susceptibility was found to be associated with the process procedure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25939628','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25939628"><span>Computed tomographic beam-<span class="hlt">hardening</span> artefacts: mathematical characterization and analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Hyoung Suk; Chung, Yong Eun; Seo, Jin Keun</p> <p>2015-06-13</p> <p>This paper presents a mathematical characterization and analysis of beam-<span class="hlt">hardening</span> artefacts in X-ray computed tomography (CT). In the field of dental and medical radiography, metal artefact reduction in CT is becoming increasingly important as artificial prostheses and metallic implants become more widespread in ageing populations. Metal artefacts are mainly caused by the beam-<span class="hlt">hardening</span> of polychromatic X-ray photon beams, which causes mismatch between the actual sinogram data and the data model being the Radon transform of the unknown attenuation distribution in the CT reconstruction algorithm. We investigate the beam-<span class="hlt">hardening</span> factor through a mathematical analysis of the discrepancy between the data and the Radon transform of the attenuation distribution at a fixed energy level. Separation of cupping artefacts from beam-<span class="hlt">hardening</span> artefacts allows causes and effects of streaking artefacts to be analysed. Various computer simulations and experiments are performed to support our mathematical analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4806379','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4806379"><span>Microscopic Origin of Strain <span class="hlt">Hardening</span> in Methane Hydrate</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jia, Jihui; Liang, Yunfeng; Tsuji, Takeshi; Murata, Sumihiko; Matsuoka, Toshifumi</p> <p>2016-01-01</p> <p>It has been reported for a long time that methane hydrate presents strain <span class="hlt">hardening</span>, whereas the strength of normal ice weakens with increasing strain after an ultimate strength. However, the microscopic origin of these differences is not known. Here, we investigated the mechanical characteristics of methane hydrate and normal ice by compressive deformation test using molecular dynamics simulations. It is shown that methane hydrate exhibits strain <span class="hlt">hardening</span> only if the hydrate is confined to a certain finite cross-sectional area that is normal to the compression direction. For normal ice, it does not present strain <span class="hlt">hardening</span> under the same conditions. We show that hydrate guest methane molecules exhibit no long-distance diffusion when confined to a finite-size area. They appear to serve as non-deformable units that prevent hydrate structure failure, and thus are responsible for the strain-<span class="hlt">hardening</span> phenomenon. PMID:27009239</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA536365','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA536365"><span>Feasibility of Underwater Friction Stir Welding of <span class="hlt">Hardenable</span> Alloy Steel</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2010-12-01</p> <p>bead-on-plate FSW traverses, approximately 64 inches (1.6 m) in total length, on 0.25 inch (6.4 mm) thick plates of a <span class="hlt">hardenable</span> alloy steel . The...base plate. Based on preliminary findings, FSW of <span class="hlt">hardenable</span> alloy steel is a feasible process and should be further researched and refined. 15...v ABSTRACT The objective of this thesis is to determine whether friction stir welding ( FSW ) is a feasible welding process for steels in an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013921','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013921"><span>Laboratory studies of <span class="hlt">volcanic</span> jets.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kieffer, S.W.; Sturtevant, B.</p> <p>1984-01-01</p> <p>Laboratory experiments to study the fluid dynamics of violent <span class="hlt">volcanic</span> eruptions employed pure gases erupted from small reservoirs. The gases used were Freon 12 and Freon 22, both of high molecular weight and high density, to model heavy, particulate- laden <span class="hlt">volcanic</span> gases; nitrogen, a moderate molecular weight and density gas with well known thermodynamic properties; and He, a low molecular weight and density gas used as an analogue of steam, the dominant gas of most <span class="hlt">volcanic</span> eruptions.-W.H.B.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160008413&hterms=encyclopedia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dencyclopedia','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160008413&hterms=encyclopedia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dencyclopedia"><span><span class="hlt">Volcanism</span> on Mars. Chapter 41</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zimbelman, J. R.; Garry, W. B.; Bleacher, J. E.; Crown, D. A.</p> <p>2015-01-01</p> <p>Spacecraft exploration has revealed abundant evidence that Mars possesses some of the most dramatic <span class="hlt">volcanic</span> landforms found anywhere within the solar system. How did a planet half the size of Earth produce volcanoes like Olympus Mons, which is several times the size of the largest volcanoes on Earth? This question is an example of the kinds of issues currently being investigated as part of the space-age scientific endeavor called "comparative planetology." This chapter summarizes the basic information currently known about <span class="hlt">volcanism</span> on Mars. The volcanoes on Mars appear to be broadly similar in overall morphology (although, often quite different in scale) to <span class="hlt">volcanic</span> features on Earth, which suggests that Martian eruptive processes are not significantly different from the <span class="hlt">volcanic</span> styles and processes on Earth. Martian volcanoes are found on terrains of different age, and Martian <span class="hlt">volcanic</span> rocks are estimated to comprise more than 50% of the Martian surface. This is in contrast to <span class="hlt">volcanism</span> on smaller bodies such as Earth's Moon, where <span class="hlt">volcanic</span> activity was mainly confined to the first half of lunar history (see "<span class="hlt">Volcanism</span> on the Moon"). Comparative planetology supports the concept that <span class="hlt">volcanism</span> is the primary mechanism for a planetary body to get rid of its internal heat; smaller bodies tend to lose their internal heat more rapidly than larger bodies (although, Jupiter's moon Io appears to contradict this trend; Io's intense <span class="hlt">volcanic</span> activity is powered by unique gravitational tidal forces within the Jovian system; see "<span class="hlt">Volcanism</span> on Io"), so that <span class="hlt">volcanic</span> activity on Mars would be expected to differ considerably from that found on Earth and the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040084685','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040084685"><span>Quantitative Studies in Planetary <span class="hlt">Volcanism</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baloga, Stephen M.</p> <p>2004-01-01</p> <p>Proxemy Research has a research grant to perform scientific investigations of <span class="hlt">volcanism</span> and <span class="hlt">volcanic</span>-related process on other planets. Part of this research involves mathematical modeling of specific <span class="hlt">volcanic</span> transport processes and the use of terrestrial analogs. This report contains a summary of activities conducted over the time period indicated. In addition, a synopsis of science research conducted during the period is given. A complete listing of publications and scientific abstracts that were presented at scientific conferences is contained in the report.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10505890','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10505890"><span>Analytical considerations of beam <span class="hlt">hardening</span> in medical accelerator photon spectra.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kleinschmidt, C</p> <p>1999-09-01</p> <p>Beam <span class="hlt">hardening</span> is a well-known phenomenon for therapeutic accelerator beams passing through matter in narrow beam geometry. This study assesses quantitatively the magnitude of beam <span class="hlt">hardening</span> of therapeutic beams in water. A formal concept of beam <span class="hlt">hardening</span> is proposed which is based on the decrease of the mean attenuation coefficient with depth. On the basis of this concept calculations of beam <span class="hlt">hardening</span> effects are easily performed by means of a commercial spreadsheet program. Published accelerator spectra and the tabulated values of attenuation coefficients serve as input for these calculations. It is shown that the mean attenuation coefficient starts at depth zero with an almost linear decrease and then slowly levels off to a limit value. A similar behavior is found for the beam <span class="hlt">hardening</span> coefficient. A physically reasonable, semianalytical model is given which fits the data better than previously published functions. The energy dependence of the initial attenuation coefficient is evaluated and shown. It fits well to published experimental data. The initial beam <span class="hlt">hardening</span> coefficient, however, shows no energy dependence. Its mean value (eta0) approximately 0.006 cm(-1)) is also in close agreement to the measured data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/415379','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/415379"><span>A study of latent <span class="hlt">hardening</span> behavior in aluminum single crystals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang Mingzhang; Lin Shi; Li Chenghua; Xiao Jimei; Wang Zhongguang</p> <p>1996-11-15</p> <p>In order to obtain a better understanding or a complete description of plastic properties of polycrystals, especially in polycrystal modelling viewpoint, investigations on latent <span class="hlt">hardening</span> behavior of single crystals have been performed in a great number. Recently, however, Wu et al. have pointed out that the definition of the yield stress of latent system using the conventional back extrapolation is ambiguous in terms of determining the latent <span class="hlt">hardening</span> moduli because the initial rapid work-<span class="hlt">hardening</span> of the transient zone is neglected. They proposed a more precise measure of the yield stress of latent system based on the decrease of the tangent modulus from the linear elastic modulus, and showed that the latent <span class="hlt">hardening</span>, which would not plus the initial work-<span class="hlt">hardening</span> of the transient zone, is actually lower than that obtained from the backward extrapolation. Thus, in their opinion, it is considered that the <span class="hlt">hardening</span> behavior of latent system (such as the directionality, the effects of relative orientation and prestrain) need be newly or further studied in detail. Single crystals of aluminum have been grown with high purity to investigate this behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5585564','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5585564"><span>Prefabricated panelized nuclear-<span class="hlt">hardened</span> shelter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smith, R.A.</p> <p>1987-08-18</p> <p>This patent describes a shelter for protecting occupants therein from dynamic blast waves and barometric overpressure created by an above ground nuclear detonation proximate to the shelter, the shelter being buried below ground under <span class="hlt">soil</span>, the <span class="hlt">soil</span> comprising means for the attenuation of the dynamic blast wave generated by the detonation, the shelter having a semipherical domed roof and a base means supporting the roof, the semipherical domed roof being downwardly displaceable and having a lower edge which is vertically and downwardly movable in response to barometric overpressure generated by the detonation, the base means being a ring made up of a plurality of arcuate sections, the arcuate sections of the base means being crushable in response to the vertical downward movement of the roof to enable the roof to move downwardly to a lower position where it is supported on the crushed base member, the overpressure being transmitted through the <span class="hlt">soil</span> surrounding the roof.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.U51A..07R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.U51A..07R"><span><span class="hlt">Volcanic</span> Eruptions and Climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robock, A.</p> <p>2012-12-01</p> <p>Large <span class="hlt">volcanic</span> eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about one year. The radiative and chemical effects of these aerosol clouds produce responses in the climate system. Observations and numerical models of the climate system show that <span class="hlt">volcanic</span> eruptions produce global cooling and were the dominant natural cause of climate change for the past millennium, on timescales from annual to century. Major tropical eruptions produce winter warming of Northern Hemisphere continents for one or two years, while high latitude eruptions in the Northern Hemisphere weaken the Asian and African summer monsoon. The Toba supereruption 74,000 years ago caused very large climate changes, affecting human evolution. However, the effects did not last long enough to produce widespread glaciation. An episode of four large decadally-spaced eruptions at the end of the 13th century C.E. started the Little Ice Age. Since the Mt. Pinatubo eruption in the Philippines in 1991, there have been no large eruptions that affected climate, but the cumulative effects of small eruptions over the past decade had a small effect on global temperature trends. The June 13, 2011 Nabro eruption in Eritrea produced the largest stratospheric aerosol cloud since Pinatubo, and the most of the sulfur entered the stratosphere not by direct injection, but by slow lofting in the Asian summer monsoon circulation. <span class="hlt">Volcanic</span> eruptions warn us that while stratospheric geoengineering could cool the surface, reducing ice melt and sea level rise, producing pretty sunsets, and increasing the CO2 sink, it could also reduce summer monsoon precipitation, destroy ozone, allowing more harmful UV at the surface, produce rapid warming when stopped, make the sky white, reduce solar power, perturb the ecology with more diffuse radiation, damage airplanes flying in the stratosphere, degrade astronomical observations, affect remote sensing, and affect</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6747539','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6747539"><span><span class="hlt">Volcanism</span> at rifts</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>White, R.S.; McKenzie, D.P.</p> <p>1989-07-01</p> <p>The earth's outer shell rifts continuously, stretching and splitting both on the ocean's floor and on continents. Every 30 million years or so the rifting becomes cataclysmic, releasing continent-size floods of magma. This paper explains that the same mechanism is at work in both cases, the difference being in the slightly hotter temperature of the parent mantle for spectacular <span class="hlt">volcanic</span> outbursts. Two kinds of evidence are described: quantitative descriptions of rock melting and a wide range of observations made on the rifted edges of continents and in the oceans that have opened between them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT.......129G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT.......129G"><span>Zinc coated sheet steel for press <span class="hlt">hardening</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghanbari, Zahra N.</p> <p></p> <p>Galvanized steels are of interest to enhance corrosion resistance of press-<span class="hlt">hardened</span> steels, but concerns related to liquid metal embrittlement have been raised. The objective of this study was to assess the soak time and temperature conditions relevant to the hot-stamping process during which Zn penetration did or did not occur in galvanized 22MnB5 press-<span class="hlt">hardening</span> steel. A GleebleRTM 3500 was used to heat treat samples using hold times and temperatures similar to those used in industrial hot-stamping. Deformation at both elevated temperature and room temperature were conducted to assess the coating and substrate behavior related to forming (at high temperature) and service (at room temperature). The extent of alloying between the coating and substrate was assessed on undeformed samples heat treated under similar conditions to the deformed samples. The coating transitioned from an α + Gamma1 composition to an α (bcc Fe-Zn) phase with increased soak time. This transition likely corresponded to a decrease in availability of Zn-rich liquid in the coating during elevated temperature deformation. Penetration of Zn into the substrate sheet in the undeformed condition was not observed for any of the processing conditions examined. The number and depth of cracks in the coating and substrate steel was also measured in the hot-ductility samples. The number of cracks appeared to increase, while the depth of cracks appeared to decrease, with increasing soak time and increasing soak temperature. The crack depth appeared to be minimized in the sample soaked at the highest soak temperature (900 °C) for intermediate and extended soak times (300 s or 600 s). Zn penetration into the substrate steel was observed in the hot-ductility samples soaked at each hold temperature for the shortest soak time (10 s) before being deformed at elevated temperature. Reduction of area and elongation measurements showed that the coated sample soaked at the highest temperature and longest soak time</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT........60M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT........60M"><span>Extracting material response from simple mechanical tests on <span class="hlt">hardening-softening-hardening</span> viscoplastic solids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohan, Nisha</p> <p></p> <p>Compliant foams are usually characterized by a wide range of desirable mechanical properties. These properties include viscoelasticity at different temperatures, energy absorption, recoverability under cyclic loading, impact resistance, and thermal, electrical, acoustic and radiation-resistance. Some foams contain nano-sized features and are used in small-scale devices. This implies that the characteristic dimensions of foams span multiple length scales, rendering modeling their mechanical properties difficult. Continuum mechanics-based models capture some salient experimental features like the linear elastic regime, followed by non-linear plateau stress regime. However, they lack mesostructural physical details. This makes them incapable of accurately predicting local peaks in stress and strain distributions, which significantly affect the deformation paths. Atomistic methods are capable of capturing the physical origins of deformation at smaller scales, but suffer from impractical computational intensity. Capturing deformation at the so-called meso-scale, which is capable of describing the phenomenon at a continuum level, but with some physical insights, requires developing new theoretical approaches. A fundamental question that motivates the modeling of foams is `how to extract the intrinsic material response from simple mechanical test data, such as stress vs. strain response?' A 3D model was developed to simulate the mechanical response of foam-type materials. The novelty of this model includes unique features such as the <span class="hlt">hardening-softening-hardening</span> material response, strain rate-dependence, and plastically compressible solids with plastic non-normality. Suggestive links from atomistic simulations of foams were borrowed to formulate a physically informed <span class="hlt">hardening</span> material input function. Motivated by a model that qualitatively captured the response of foam-type vertically aligned carbon nanotube (VACNT) pillars under uniaxial compression [2011,"Analysis of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070032045','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070032045"><span>High-Performance, Radiation-<span class="hlt">Hardened</span> Electronics for Space Environments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keys, Andrew S.; Watson, Michael D.; Frazier, Donald O.; Adams, James H.; Johnson, Michael A.; Kolawa, Elizabeth A.</p> <p>2007-01-01</p> <p>The Radiation <span class="hlt">Hardened</span> Electronics for Space Environments (RHESE) project endeavors to advance the current state-of-the-art in high-performance, radiation-<span class="hlt">hardened</span> electronics and processors, ensuring successful performance of space systems required to operate within extreme radiation and temperature environments. Because RHESE is a project within the Exploration Technology Development Program (ETDP), RHESE's primary customers will be the human and robotic missions being developed by NASA's Exploration Systems Mission Directorate (ESMD) in partial fulfillment of the Vision for Space Exploration. Benefits are also anticipated for NASA's science missions to planetary and deep-space destinations. As a technology development effort, RHESE provides a broad-scoped, full spectrum of approaches to environmentally <span class="hlt">harden</span> space electronics, including new materials, advanced design processes, reconfigurable hardware techniques, and software modeling of the radiation environment. The RHESE sub-project tasks are: SelfReconfigurable Electronics for Extreme Environments, Radiation Effects Predictive Modeling, Radiation <span class="hlt">Hardened</span> Memory, Single Event Effects (SEE) Immune Reconfigurable Field Programmable Gate Array (FPGA) (SIRF), Radiation <span class="hlt">Hardening</span> by Software, Radiation <span class="hlt">Hardened</span> High Performance Processors (HPP), Reconfigurable Computing, Low Temperature Tolerant MEMS by Design, and Silicon-Germanium (SiGe) Integrated Electronics for Extreme Environments. These nine sub-project tasks are managed by technical leads as located across five different NASA field centers, including Ames Research Center, Goddard Space Flight Center, the Jet Propulsion Laboratory, Langley Research Center, and Marshall Space Flight Center. The overall RHESE integrated project management responsibility resides with NASA's Marshall Space Flight Center (MSFC). Initial technology development emphasis within RHESE focuses on the <span class="hlt">hardening</span> of Field Programmable Gate Arrays (FPGA)s and Field Programmable Analog</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70138607','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70138607"><span>Uranium series, <span class="hlt">volcanic</span> rocks</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Vazquez, Jorge A.</p> <p>2014-01-01</p> <p>Application of U-series dating to <span class="hlt">volcanic</span> rocks provides unique and valuable information about the absolute timing of crystallization and differentiation of magmas prior to eruption. The 238U–230Th and 230Th-226Ra methods are the most commonly employed for dating the crystallization of mafic to silicic magmas that erupt at volcanoes. Dates derived from the U–Th and Ra–Th methods reflect crystallization because diffusion of these elements at magmatic temperatures is sluggish (Cherniak 2010) and diffusive re-equilibration is insignificant over the timescales (less than or equal to 10^5 years) typically associated with pre-eruptive storage of nearly all magma compositions (Cooper and Reid 2008). Other dating methods based on elements that diffuse rapidly at magmatic temperatures, such as the 40Ar/39Ar and (U–Th)/He methods, yield dates for the cooling of magma at the time of eruption. Disequilibrium of some short-lived daughters of the uranium series such as 210Po may be fractionated by saturation of a volatile phase and can be employed to date magmatic gas loss that is synchronous with <span class="hlt">volcanic</span> eruption (e.g., Rubin et al. 1994).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160000376&hterms=Volcanic+Eruptions&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DVolcanic%2BEruptions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160000376&hterms=Volcanic+Eruptions&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DVolcanic%2BEruptions"><span><span class="hlt">Volcanic</span> Eruptions and Climate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>LeGrande, Allegra N.; Anchukaitis, Kevin J.</p> <p>2015-01-01</p> <p><span class="hlt">Volcanic</span> eruptions represent some of the most climatically important and societally disruptive short-term events in human history. Large eruptions inject ash, dust, sulfurous gases (e.g. SO2, H2S), halogens (e.g. Hcl and Hbr), and water vapor into the Earth's atmosphere. Sulfurous emissions principally interact with the climate by converting into sulfate aerosols that reduce incoming solar radiation, warming the stratosphere and altering ozone creation, reducing global mean surface temperature, and suppressing the hydrological cycle. In this issue, we focus on the history, processes, and consequences of these large eruptions that inject enough material into the stratosphere to significantly affect the climate system. In terms of the changes wrought on the energy balance of the Earth System, these transient events can temporarily have a radiative forcing magnitude larger than the range of solar, greenhouse gas, and land use variability over the last millennium. In simulations as well as modern and paleoclimate observations, <span class="hlt">volcanic</span> eruptions cause large inter-annual to decadal-scale changes in climate. Active debates persist concerning their role in longer-term (multi-decadal to centennial) modification of the Earth System, however.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70042390','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70042390"><span>Rapid response of a hydrologic system to <span class="hlt">volcanic</span> activity: Masaya volcano, Nicaragua</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pearson, S.C.P.; Connor, C.B.; Sanford, W.E.</p> <p>2008-01-01</p> <p>Hydrologic systems change in response to <span class="hlt">volcanic</span> activity, and in turn may be sensitive indicators of <span class="hlt">volcanic</span> activity. Here we investigate the coupled nature of magmatic and hydrologic systems using continuous multichannel time series of <span class="hlt">soil</span> temperature collected on the flanks of Masaya volcano, Nicaragua, one of the most active volcanoes in Central America. The <span class="hlt">soil</span> temperatures were measured in a low-temperature fumarole field located 3.5 km down the flanks of the volcano. Analysis of these time series reveals that they respond extremely rapidly, on a time scale of minutes, to changes in <span class="hlt">volcanic</span> activity also manifested at the summit vent. These rapid temperature changes are caused by increased flow of water vapor through flank fumaroles during <span class="hlt">volcanism</span>. The <span class="hlt">soil</span> temperature response, ~5 °C, is repetitive and complex, with as many as 13 pulses during a single <span class="hlt">volcanic</span> episode. Analysis of the frequency spectrum of these temperature time series shows that these anomalies are characterized by broad frequency content during <span class="hlt">volcanic</span> activity. They are thus easily distinguished from seasonal trends, diurnal variations, or individual rainfall events, which triggered rapid transient increases in temperature during 5% of events. We suggest that the mechanism responsible for the distinctive temperature signals is rapid change in pore pressure in response to magmatism, a response that can be enhanced by meteoric water infiltration. Monitoring of distal fumaroles can therefore provide insight into coupled <span class="hlt">volcanic</span>-hydrologic-meteorologic systems, and has potential as an inexpensive monitoring tool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21516733','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21516733"><span>Process design of press <span class="hlt">hardening</span> with gradient material property influence</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Neugebauer, R.; Schieck, F.; Rautenstrauch, A.</p> <p>2011-05-04</p> <p>Press <span class="hlt">hardening</span> is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press <span class="hlt">hardening</span> can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press <span class="hlt">hardening</span> owing to their excellent hot formability, high <span class="hlt">hardenability</span>, and good temperability even at low cooling rates. However, press-<span class="hlt">hardened</span> components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press <span class="hlt">hardening</span> process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press <span class="hlt">hardening</span> of sheet components with gradient material properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21584756','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21584756"><span>Bacterial diversity of terrestrial crystalline <span class="hlt">volcanic</span> rocks, Iceland.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kelly, Laura C; Cockell, Charles S; Herrera-Belaroussi, Aude; Piceno, Yvette; Andersen, Gary; DeSantis, Todd; Brodie, Eoin; Thorsteinsson, Thorsteinn; Marteinsson, Viggó; Poly, Franck; LeRoux, Xavier</p> <p>2011-07-01</p> <p>Bacteria inhabiting crystalline rocks from two terrestrial Icelandic <span class="hlt">volcanic</span> lava flows of similar age and from the same geographical region, but differing in porosity and mineralogy, were characterised. Microarray (PhyloChip) and clone library analysis of 16S rRNA genes revealed the presence of a diverse assemblage of bacteria in each lava flow. Both methods suggested a more diverse community at the Dómadalshraun site (rhyolitic/andesitic lava flow) than that present at the Hnausahraun site (basaltic lava flow). Proteobacteria dominated the clone library at the Dómadalshraun site, while Acidobacteria was the most abundant phylum in the Hnausahraun site. Although analysis of similarities of denaturing gradient gel electrophoresis profiles suggested a strong correlation of community structure with mineralogy, rock porosity may also play an important role in shaping the bacterial community in crystalline <span class="hlt">volcanic</span> rocks. Clone sequences were most similar to uncultured microorganisms, mainly from <span class="hlt">soil</span> environments. Of these, Antarctic <span class="hlt">soils</span> and temperate rhizosphere <span class="hlt">soils</span> were prominent, as were clones retrieved from Hawaiian and Andean <span class="hlt">volcanic</span> <span class="hlt">soils</span>. The novel diversity of these Icelandic microbial communities was supported by the finding that up to 46% of clones displayed <85% sequence identities to sequences currently deposited in the RDP database.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008SSRv..137..399J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008SSRv..137..399J"><span>Electrical Charging of <span class="hlt">Volcanic</span> Plumes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>James, M. R.; Wilson, L.; Lane, S. J.; Gilbert, J. S.; Mather, T. A.; Harrison, R. G.; Martin, R. S.</p> <p>2008-06-01</p> <p>Many explosive terrestrial <span class="hlt">volcanic</span> eruptions are accompanied by lightning and other atmospheric electrical phenomena. The plumes produced generate large perturbations in the surface atmospheric electric potential gradient and high charge densities have been measured on falling <span class="hlt">volcanic</span> ash particles. The complex nature of <span class="hlt">volcanic</span> plumes (which contain gases, solid particles, and liquid drops) provides several possible charging mechanisms. For plumes rich in solid silicate particles, fractoemission (the ejection of ions and atomic particles during fracture events) is probably the dominant source of charge generation. In other plumes, such as those created when lava enters the sea, different mechanisms, such as boiling, may be important. Further charging mechanisms may also subsequently operate, downwind of the vent. Other solar system bodies also show evidence for <span class="hlt">volcanism</span>, with activity ongoing on Io. Consequently, <span class="hlt">volcanic</span> electrification under different planetary scenarios (on Venus, Mars, Io, Moon, Enceladus, Tethys, Dione and Triton) is also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008pae..book..399J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008pae..book..399J"><span>Electrical Charging of <span class="hlt">Volcanic</span> Plumes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>James, M. R.; Wilson, L.; Lane, S. J.; Gilbert, J. S.; Mather, T. A.; Harrison, R. G.; Martin, R. S.</p> <p></p> <p>Many explosive terrestrial <span class="hlt">volcanic</span> eruptions are accompanied by lightning and other atmospheric electrical phenomena. The plumes produced generate large perturbations in the surface atmospheric electric potential gradient and high charge densities have been measured on falling <span class="hlt">volcanic</span> ash particles. The complex nature of <span class="hlt">volcanic</span> plumes (which contain gases, solid particles, and liquid drops) provides several possible charging mechanisms. For plumes rich in solid silicate particles, fractoemission (the ejection of ions and atomic particles during fracture events) is probably the dominant source of charge generation. In other plumes, such as those created when lava enters the sea, different mechanisms, such as boiling, may be important. Further charging mechanisms may also subsequently operate, downwind of the vent. Other solar system bodies also show evidence for <span class="hlt">volcanism</span>, with activity ongoing on Io. Consequently, <span class="hlt">volcanic</span> electrification under different planetary scenarios (on Venus, Mars, Io, Moon, Enceladus, Tethys, Dione and Triton) is also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.1592K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.1592K"><span>Friction in <span class="hlt">volcanic</span> environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kendrick, Jackie E.; Lavallée, Yan</p> <p>2016-04-01</p> <p><span class="hlt">Volcanic</span> landscapes are amongst the most dynamic on Earth and, as such, are particularly susceptible to failure and frictional processes. In rocks, damage accumulation is frequently accompanied by the release of seismic energy, which has been shown to accelerate in the approach to failure on both a field and laboratory scale. The point at which failure occurs is highly dependent upon strain-rate, which also dictates the slip-zone properties that pertain beyond failure, in scenarios such as sector collapse and pyroclastic flows as well as the ascent of viscous magma. High-velocity rotary shear (HVR) experiments have provided new opportunities to overcome the grand challenge of understanding faulting processes during <span class="hlt">volcanic</span> phenomena. Work on granular ash material demonstrates that at ambient temperatures, ash gouge behaves according to Byerlee's rule at low slip velocities, but is slip-weakening, becoming increasingly lubricating as slip ensues. In absence of ash along a slip plane, rock-rock friction induces cataclasis and heating which, if sufficient, may induce melting (producing pseudotachylyte) and importantly, vesiculation. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The shear-thinning behaviour and viscoelasticity of frictional melts yield a tendency for extremely unstable slip, and occurrence of frictional melt fragmentation. This velocity-dependence acts as an important feedback mechanism on the slip plane, in addition to the bulk composition, mineralogy and glass content of the magma, that all influence frictional behaviour. During sector collapse events and in pyroclastic density currents it is the frictional properties of the rocks and ash that, in-part, control the run-out distance and associated risk. In addition, friction plays an important role in the eruption of viscous magmas: In the conduit, the rheology of magma is integral</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.B42A..06F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.B42A..06F"><span>Biogeochemistry and nitrogen cycling in an Arctic, <span class="hlt">volcanic</span> ecosystem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fogel, M. L.; Benning, L.; Conrad, P. G.; Eigenbrode, J.; Starke, V.</p> <p>2007-12-01</p> <p>As part of a study on Mars Analogue environments, the biogeochemistry of Sverrefjellet Volcano, Bocfjorden, Svalbard, was conducted and compared to surrounding glacial, thermal spring, and sedimentary environments. An understanding of how nitrogen might be distributed in a landscape that had extinct or very cold adapted, slow- growing extant organisms should be useful for detecting unknown life forms. From high elevations (900 m) to the base of the volcano (sea level), <span class="hlt">soil</span> and rock ammonium concentrations were uniformly low, typically less than 1- 3 micrograms per gm of rock or <span class="hlt">soil</span>. In weathered <span class="hlt">volcanic</span> <span class="hlt">soils</span>, reduced nitrogen concentrations were higher, and oxidized nitrogen concentrations lower. The opposite was found in a weathered Devonian sedimentary <span class="hlt">soil</span>. Plants and lichens growing on <span class="hlt">volcanic</span> <span class="hlt">soils</span> have an unusually wide range in N isotopic compositions from -5 to +12‰, a range rarely measured in temperate ecosystems. Nitrogen contents and isotopic compositions of <span class="hlt">volcanic</span> <span class="hlt">soils</span> and rocks were strongly influenced by the presence or absence of terrestrial herbivores or marine avifauna with higher concentrations of N and elevated N isotopic compositions occurring as patches in areas immediately influenced by reindeer, Arctic fox ( Alopex lagopus), and marine birds. Because of the extreme conditions in this area, ephemeral deposition of herbivore feces results in a direct and immediate N pulses into the ecosystem. The lateral extent and distribution of marine- derived nitrogen was measured on a landscape scale surrounding an active fox den. Nitrogen was tracked from the bones of marine birds to <span class="hlt">soil</span> to vegetation. Because of extreme cold, slow biological rates and nitrogen cycling, a mosaic of N patterns develops on the landscape scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/676873','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/676873"><span>Solute <span class="hlt">hardening</span> and softening effects in B2 nickel aluminides</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pike, L.M.; Liu, C.T.; Anderson, I.M.; Chang, Y.A.</p> <p>1998-11-01</p> <p>The effect of substitutional solute additions including Fe, Mn, and Pd on the hardness of B2-ordered NiAl alloys was investigated. The solid solution <span class="hlt">hardening</span> behavior of intermetallics is more complex than that of typical metallic solid solutions because of complications arising from the site preference of the solute as well as the effects of the solute on the concentrations of other point defects, e.g., vacancies and anti-site defects. For this reason, care was taken to experimentally establish solute site preferences and point defect concentrations in the NiAl alloys before analyzing the hardness data. By taking these factors into account it was possible to rationalize the observed unusual <span class="hlt">hardening</span> effects. Three distinct categories of solid solution <span class="hlt">hardening</span> behavior were encountered. The first was <span class="hlt">hardening</span> by the solute addition itself. This was observed in the case of Pd additions to Al-poor NiAl. However, when fe or Mn is added to Al-poor NiAl a second category is observed; these elements are seen to soften the material. The third category of behavior is observed when Fe is added to NiAl with a constant Al concentration of 50 at. %. In this case it is vacancies, rather than solute atoms, which <span class="hlt">harden</span> the material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009MS%26E....4a2014W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009MS%26E....4a2014W"><span>Computer modelling of age <span class="hlt">hardening</span> for cast aluminium alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Linda; Ferguson, W. George</p> <p>2009-08-01</p> <p>Age <span class="hlt">hardening</span>, or precipitation <span class="hlt">hardening</span>, is one of the most widely adopted techniques for strengthening of aluminium alloys. Although various age <span class="hlt">hardening</span> models have been developed for aluminium alloys, from the large volume of literature reviewed, it appears that the bulk of the research has been concentrated on wrought aluminium alloys, only a few of the established precipitation models have been applied to the casting aluminium alloys. In the present work, there are two modelling methods that have been developed and applied to the casting aluminium alloys A356 and A357. One is based on the Shercliff-Ashby methodology to produce a process model, by which we mean a mathematical relationship between process variables (alloy composition, ageing temperature and time) and material properties (yield strength or hardness) through microstructure evolution (precipitate radius, volume fraction). The other method is based on the Kampmann and Wagner Numerical (KWN) model which deals with concomitant nucleation, growth and coarsening and is thus capable of predicting the full evolution of the particle size distribution and then a strength model is used to evaluate the resulting change in hardness or yield strength at room temperature by taking into account contributions from lattice resistance, solid solution <span class="hlt">hardening</span> and precipitation <span class="hlt">hardening</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10180923','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10180923"><span><span class="hlt">Volcanic</span> studies at Katmai</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1989-12-31</p> <p>The Continental Scientific Drilling Program (CSDP) is a national effort supported by the Department of Energy, the US Geological Survey, and the National Science Foundation. One of the projects proposed for the CSDP consists of drilling a series of holes in Katmai National Park in Alaska to give a third dimension to the model of the 1912 eruption of Novarupta, and to investigate the processes of explosive <span class="hlt">volcanism</span> and hydrothermal transport of metals (Eichelberger et al., 1988). The proposal for research drilling at Katmai states that ``the size, youth, elevated temperature, and simplicity of the Novarupta vent make it a truly unique scientific target.`` The National Park Service (NPS), which has jurisdiction, is sympathetic to aims of the study. However, NPS wishes to know whether Katmai is indeed uniquely suited to the research, and has asked the Interagency Coordinating Group to support an independent assessment of this claim. NPS suggested the National Academy of Sciences as an appropriate organization to conduct the assessment. In response, the National Research Council -- the working arm of the Academy -- established, under the aegis of its US Geodynamics Committee, a panel whose specific charge states: ``The proposed investigation at Katmai has been extensively reviewed for scientific merit by the three sponsoring and participating agencies. Thus, the scientific merit of the proposed drilling at Katmai is not at issue. The panel will review the proposal for scientific drilling at Katmai and prepare a short report addressing the specific question of the degree to which it is essential that the drilling be conducted at Katmai as opposed to <span class="hlt">volcanic</span> areas elsewhere in the world.``</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27155095','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27155095"><span>Hazardous indoor CO2 concentrations in <span class="hlt">volcanic</span> environments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Viveiros, Fátima; Gaspar, João L; Ferreira, Teresa; Silva, Catarina</p> <p>2016-07-01</p> <p>Carbon dioxide is one of the main <span class="hlt">soil</span> gases released silently and permanently in diffuse degassing areas, both in <span class="hlt">volcanic</span> and non-<span class="hlt">volcanic</span> zones. In the <span class="hlt">volcanic</span> islands of the Azores (Portugal) several villages are located over diffuse degassing areas. Lethal indoor CO2 concentrations (higher than 10 vol %) were measured in a shelter located at Furnas village, inside the caldera of the quiescent Furnas Volcano (S. Miguel Island). Hazardous CO2 concentrations were detected not only underground, but also at the ground floor level. Multivariate regression analysis was applied to the CO2 and environmental time series recorded between April 2008 and March 2010 at Furnas village. The results show that about 30% of the indoor CO2 variation is explained by environmental variables, namely barometric pressure, <span class="hlt">soil</span> water content and wind speed. The highest indoor CO2 concentrations were recorded during bad weather conditions, characterized by low barometric pressure together with rainfall periods and high wind speed. In addition to the spike-like changes observed on the CO2 time series, long-term oscillations were also identified and appeared to represent seasonal variations. In fact, indoor CO2 concentrations were higher during winter period when compared to the dry summer months. Considering the permanent emission of CO2 in various <span class="hlt">volcanic</span> regions of the world, CO2 hazard maps are crucial and need to be accounted by the land-use planners and authorities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22573915','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22573915"><span>Branching structure and strain <span class="hlt">hardening</span> of branched metallocene polyethylenes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Torres, Enrique; Li, Si-Wan; Costeux, Stéphane; Dealy, John M.</p> <p>2015-09-15</p> <p>There have been a number of studies of a series of branched metallocene polyethylenes (BMPs) made in a solution, continuous stirred tank reactor (CSTR) polymerization. The materials studied vary in branching level in a systematic way, and the most highly branched members of the series exhibit mild strain <span class="hlt">hardening</span>. An outstanding question is which types of branched molecules are responsible for strain <span class="hlt">hardening</span> in extension. This question is explored here by use of polymerization and rheological models along with new data on the extensional flow behavior of the most highly branched members of the set. After reviewing all that is known about the effects of various branching structures in homogeneous polymers and comparing this with the structures predicted to be present in BMPs, it is concluded that in spite of their very low concentration, treelike molecules with branch-on-branch structure provide a large number of deeply buried inner segments that are essential for strain <span class="hlt">hardening</span> in these polymers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/863388','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/863388"><span>Secondary <span class="hlt">hardening</span> steel having improved combination of hardness and toughness</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Parker, Earl R.; Zackay, Victor F.; Bhat, Manjeshwar S.; Garrison, Jr., Warren M.</p> <p>1979-01-01</p> <p>A secondary <span class="hlt">hardening</span> alloy steel composition consisting essentially of about 0.25-0.5% carbon, about 0.5-1.0% manganese, about 1.5-3.0% nickel, about 0-1.0% chromium, about 1.75-2.5% molybdenum, about 0-0.4% vanadium, and an additive selected from about 1-3% aluminum and a combination of at least about 1% aluminum and at least about 1% silicon for a combined Al+Si content of about 2-4%, the balance being iron and impurity elements. The present steel composition has the following characteristics: it exhibits a flat tempering response, it is <span class="hlt">hardenable</span> upon tempering to a Rockwell C hardness of at least 50, and it has an improved combination of hardness vs. toughness properties after tempering in the secondary <span class="hlt">hardening</span> range. A method of preparation is also described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JNuM..296..203H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JNuM..296..203H"><span>Ion-irradiation-induced <span class="hlt">hardening</span> in Inconel 718</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hunn, J. D.; Lee, E. H.; Byun, T. S.; Mansur, L. K.</p> <p>2001-07-01</p> <p>Inconel 718 is a material under consideration for areas in the target region of the spallation neutron source (SNS), now under construction at Oak Ridge National Laboratory (ORNL) in the US. In these positions, displacement damage from protons and neutrons will affect the mechanical properties. In addition, significant amounts of helium and hydrogen will build up in the material due to transmutation reactions. Nanoindentation measurements of solution-annealed (SA) Inconel 718 specimens, implanted with Fe-, He-, and H-ions to simulate SNS target radiation conditions, have shown that <span class="hlt">hardening</span> occurs due to ion-induced displacement damage as well as due to the build-up of helium bubbles in the irradiated layer. Precipitation-<span class="hlt">hardened</span> (PH) Inconel 718 also exhibited <span class="hlt">hardening</span> by helium build-up but showed softening as a function of displacement damage due to dissolution of the γ ' and γ″ precipitates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21061744','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21061744"><span>Kinematic <span class="hlt">Hardening</span>: Characterization, Modeling and Impact on Springback Prediction</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Alves, J. L.; Bouvier, S.; Jomaa, M.; Billardon, R.</p> <p>2007-05-17</p> <p>The constitutive modeling of the materials' mechanical behavior, usually carried out using a phenomenological constitutive model, i.e., a yield criterion associated to the isotropic and kinematic <span class="hlt">hardening</span> laws, is of paramount importance in the FEM simulation of the sheet metal forming processes, as well as in the springback prediction. Among others, the kinematic behavior of the yield surface plays an essential role, since it is indispensable to describe the Bauschinger effect, i.e., the materials' answer to the multiple tension-compression cycles to which material points are submitted during the forming process. Several laws are usually used to model and describe the kinematic <span class="hlt">hardening</span>, namely: a) the Prager's law, which describes a linear evolution of the kinematic <span class="hlt">hardening</span> with the plastic strain rate tensor b) the Frederick-Armstrong non-linear kinematic <span class="hlt">hardening</span>, basically a non-linear law with saturation; and c) a more advanced physically-based law, similar to the previous one but sensitive to the strain path changes. In the present paper a mixed kinematic <span class="hlt">hardening</span> law (linear + non-linear behavior) is proposed and its implementation into a static fully-implicit FE code is described. The material parameters identification for sheet metals using different strategies, and the classical Bauschinger loading tests (i.e. in-plane forward and reverse monotonic loading), are addressed, and their impact on springback prediction evaluated. Some numerical results concerning the springback prediction of the Numisheet'05 Benchmark no. 3 are briefly presented to emphasize the importance of a correct modeling and identification of the kinematic <span class="hlt">hardening</span> behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20726152','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20726152"><span>Determination of Anisotropic <span class="hlt">Hardening</span> of Sheet Metals by Shear Tests</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schikorra, Marco; Brosius, Alexander; Kleiner, Matthias</p> <p>2005-08-05</p> <p>With regard to the increasing necessity of accurate material data determination for the prediction of springback, a material testing equipment has been developed and set up for the measurement of material <span class="hlt">hardening</span> within cyclic loading. One reason for inaccurate springback predictions can be seen in a missing consideration of load reversal effects in a realistic material model description. Due to bending and unbending while the material is drawn from the flange over a radius of a deep drawing tool, a <span class="hlt">hardening</span> takes place which leads to an expanding or shifting of the elastic area and yield locus known as isotropic, kinematic, or combined <span class="hlt">hardening</span>. Since springback is mainly influenced by the actual stress state and a correct distinction between elastic and elastic-plastic regions, an accurate prediction of these stress and strain components is basically required to simulate springback accurately, too. The presented testing method deals with shearing of sheet metal specimens in one or more load cycles to analyze the change of yield point and yield curve. The experimental set up is presented and discussed and the results are shown for different materials such as aluminum A199.5, stainless steel X5CrNi18.10, dual phase steel DP600, and copper Cu99.99. To guarantee a wide experimental range, different sheet thicknesses were used additionally. Simulations using the finite element method were carried out to compare the measured results with calculated results from different yield criterions and different <span class="hlt">hardening</span> laws mentioned above. It was possible to show that commonly used standard material <span class="hlt">hardening</span> laws like isotropic and kinematic <span class="hlt">hardening</span> laws often do not lead to accurate stress state predictions when load reversals occur. The work shows the range of occurring differences and strategies to obtain to a more reliable prediction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010062480','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010062480"><span>Quantitative Studies in Planetary <span class="hlt">Volcanism</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baloga, Stephen M.</p> <p>2001-01-01</p> <p>Scientific research was conducted on <span class="hlt">volcanic</span> processes on Mars, Venus, Io, the moon, and the Earth. The achievements led to scientific advances in the understanding of <span class="hlt">volcanic</span> plumes, lava flow emplacements, coronae, and regoliths on the solid surfaces. This research led to multiple publications on each of the main topics of the proposal. Research was also presented at the annual Lunar and Planetary Science Conference at Houston. Typically, this grant contributed to 3-4 presentations each year. This grant demonstrated, numerous times, the usefulness of NASA mission data for advancing the understanding of <span class="hlt">volcanic</span> processes on other planetary surfaces and the Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6094570','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6094570"><span>Closer look at lunar <span class="hlt">volcanism</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vaniman, D.T.; Heiken, G.; Taylor, G.J.</p> <p>1984-01-01</p> <p>Although the American Apollo and Soviet Luna missions concentrated on mare basalt samples, major questions remain about lunar <span class="hlt">volcanism</span>. Lunar field work will be indispensable for resolving the scientific questions about ages, compositions, and eruption processes of lunar <span class="hlt">volcanism</span>. From a utilitarian standpoint, a better knowledge of lunar <span class="hlt">volcanism</span> will also yield profitable returns in lunar base construction (e.g., exploitation of rille or lava-tube structures) and in access to materials such as volatile elements, pure glass, or ilmenite for lunar industry.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/750190','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/750190"><span>Why semiconductors must be <span class="hlt">hardened</span> when used in space</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Winokur, P. S.</p> <p>2000-01-04</p> <p>The natural space radiation environment presents a great challenge to present and future satellite systems with significant assets in space. Defining requirements for such systems demands knowledge about the space radiation environment and its effects on electronics and optoelectronics technologies, as well as suitable risk assessment of the uncertainties involved. For mission of high radiation levels, radiation-<span class="hlt">hardened</span> integrated circuits will be required to preform critical mission functions. The most successful systems in space will be those that are best able to blend standard commercial electronics with custom radiation-<span class="hlt">hardened</span> electronics in a mix that is suitable for the system of interest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ApPhL.100y1909D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ApPhL.100y1909D"><span>Atomistic mechanisms of cyclic <span class="hlt">hardening</span> in metallic glass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deng, Chuang; Schuh, Christopher A.</p> <p>2012-06-01</p> <p>Molecular dynamics with an embedded-atom method potential is used to simulate the nanoindentation of Cu63.5Zr36.5 metallic glasses. In particular, the effects of cyclic loading within the nominal elastic range on the overall strength and plasticity of metallic glass are studied. The simulated results are in line with the characteristics of experimentally observed <span class="hlt">hardening</span> effects. In addition, analysis based on local von Mises strain suggests that the <span class="hlt">hardening</span> is induced by confined microplasticity and stiffening in regions of the originally preferred yielding path, requiring a higher applied load to trigger a secondary one.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17930472','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17930472"><span>Strain <span class="hlt">hardening</span> in polymer glasses: limitations of network models.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoy, Robert S; Robbins, Mark O</p> <p>2007-09-14</p> <p>Simulations are used to examine the microscopic origins of strain <span class="hlt">hardening</span> in polymer glasses. While traditional entropic network models can be fit to the total stress, their underlying assumptions are inconsistent with simulation results. There is a substantial energetic contribution to the stress that rises rapidly as segments between entanglements are pulled taut. The thermal component of stress is less sensitive to entanglements, mostly irreversible, and directly related to the rate of local plastic rearrangements. Entangled and unentangled chains show the same strain <span class="hlt">hardening</span> when plotted against the microscopic chain orientation rather than the macroscopic strain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26465444','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26465444"><span>Statistical thermodynamics of strain <span class="hlt">hardening</span> in polycrystalline solids.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Langer, J S</p> <p>2015-09-01</p> <p>This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman [Acta Mat. 58, 3718 (2010)ACMAFD1359-645410.1016/j.actamat.2010.03.009]. It then uses that theory to explain the anomalous rate-<span class="hlt">hardening</span> behavior reported in 1988 by Follansbee and Kocks and to explore the relation between <span class="hlt">hardening</span> rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/869372','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/869372"><span>Method and apparatus for welding precipitation <span class="hlt">hardenable</span> materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Murray, Jr., Holt; Harris, Ian D.; Ratka, John O.; Spiegelberg, William D.</p> <p>1994-01-01</p> <p>A method for welding together members consisting of precipitation age <span class="hlt">hardened</span> materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age <span class="hlt">hardening</span> characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7175974','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/7175974"><span>Method and apparatus for welding precipitation <span class="hlt">hardenable</span> materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Murray, H. Jr.; Harris, I.D.; Ratka, J.O.; Spiegelberg, W.D.</p> <p>1994-06-28</p> <p>A method for welding together members consisting of precipitation age <span class="hlt">hardened</span> materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age <span class="hlt">hardening</span> characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined. 5 figures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050245195','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050245195"><span>Impact of Scaled Technology on Radiation Testing and <span class="hlt">Hardening</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>LaBel, Kenneth A.; Cohn, Lewis M.</p> <p>2005-01-01</p> <p>This presentation gives a brief overview of some of the radiation challenges facing emerging scaled digital technologies with implications on using consumer grade electronics and next generation <span class="hlt">hardening</span> schemes. Commercial semiconductor manufacturers are recognizing some of these issues as issues for terrestrial performance. Looking at means of dealing with soft errors. The thinned oxide has indicated improved TID tolerance of commercial products <span class="hlt">hardened</span> by "serendipity" which does not guarantee hardness or say if the trend will continue. This presentation also focuses one reliability implications of thinned oxides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22475522','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22475522"><span>Temperature influence on water transport in <span class="hlt">hardened</span> cement pastes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Drouet, Emeline; Poyet, Stéphane; Torrenti, Jean-Michel</p> <p>2015-10-15</p> <p>Describing water transport in concrete is an important issue for the durability assessment of radioactive waste management reinforced concrete structures. Due to the waste thermal output such structures would be submitted to moderate temperatures (up to 80 °C). We have then studied the influence of temperature on water transport within <span class="hlt">hardened</span> cement pastes of four different formulations. Using a simplified approach (describing only the permeation of liquid water) we characterized the properties needed to describe water transport (up to 80 °C) using dedicated experiments. For each <span class="hlt">hardened</span> cement paste the results are presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20748667','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20748667"><span>Precipitation <span class="hlt">hardening</span> of a novel aluminum matrix composite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Suarez, Oscar Marcelo</p> <p>2002-09-15</p> <p>Deterioration of properties in cast aluminum matrix composites (AMCs) due to matrix/reinforcement chemical reactions is absent when AlB{sub 2} particles are used as reinforcements. This communication reports the fabrication of a heat-treatable AMC reinforced with borides. Final hardness values can be adjusted by solution and precipitation, which <span class="hlt">harden</span> the composite. Evolution of the microstructure is concisely presented as observed by secondary electron microscopy. Precipitation <span class="hlt">hardening</span> of the aluminum matrix, observed by microhardness measurements, has been corroborated by differential thermal analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1223661-statistical-thermodynamics-strain-hardening-polycrystalline-solids','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1223661-statistical-thermodynamics-strain-hardening-polycrystalline-solids"><span>Statistical thermodynamics of strain <span class="hlt">hardening</span> in polycrystalline solids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Langer, James S.</p> <p>2015-09-18</p> <p>This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman. The paper then uses that theory to explain the anomalous rate-<span class="hlt">hardening</span> behavior reported in 1988 by Follansbee and Kocks and to explore the relation between <span class="hlt">hardening</span> rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhRvL..99k7801H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhRvL..99k7801H"><span>Strain <span class="hlt">Hardening</span> in Polymer Glasses: Limitations of Network Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hoy, Robert S.; Robbins, Mark O.</p> <p>2007-09-01</p> <p>Simulations are used to examine the microscopic origins of strain <span class="hlt">hardening</span> in polymer glasses. While traditional entropic network models can be fit to the total stress, their underlying assumptions are inconsistent with simulation results. There is a substantial energetic contribution to the stress that rises rapidly as segments between entanglements are pulled taut. The thermal component of stress is less sensitive to entanglements, mostly irreversible, and directly related to the rate of local plastic rearrangements. Entangled and unentangled chains show the same strain <span class="hlt">hardening</span> when plotted against the microscopic chain orientation rather than the macroscopic strain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HESS...20.1133Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HESS...20.1133Y"><span>Coevolution of <span class="hlt">volcanic</span> catchments in Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshida, Takeo; Troch, Peter A.</p> <p>2016-03-01</p> <p>Present-day landscapes have evolved over time through interactions between the prevailing climates and geological settings. Understanding the linkage between spatial patterns of landforms, <span class="hlt">soils</span>, and vegetation in landscapes and their hydrological response is critical to make quantitative predictions in ungaged basins. Catchment coevolution is a theoretical framework that seeks to formulate hypotheses about the mechanisms and conditions that determine the historical development of catchments and how such evolution affects their hydrological response. In this study, we selected 14 <span class="hlt">volcanic</span> catchments of different ages (from 0.225 to 82.2 Ma) in Japan. We derived indices of landscape properties (drainage density and slope-area relationship) as well as hydrological response (annual water balance, baseflow index, and flow-duration curves) and examined their relation with catchment age and climate (through the aridity index). We found a significant correlation between drainage density and baseflow index with age, but not with climate. The intra-annual flow variability was also significantly related to catchments age. Younger catchments tended to have lower peak flows and higher low flows, while older catchments exhibited more flashy runoff. The decrease in baseflow with catchment age is consistent with the existing hypothesis that in <span class="hlt">volcanic</span> landscapes the major flow pathways change over time from deep groundwater flow to shallow subsurface flow. The drainage density of our catchments decreased with age, contrary to previous findings in a set of similar, but younger <span class="hlt">volcanic</span> catchments in the Oregon Cascades, in which drainage density increased with age. In that case, older catchments were thought to show more landscape incision due to increasing near-surface lateral flow paths. Our results suggests two competing hypotheses on the evolution of drainage density in mature catchments. One is that as catchments continue to age, the hydrologically active channels retreat</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989IssZK...4...44I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989IssZK...4...44I"><span>Optical mapping of Kamchatka's <span class="hlt">volcanic</span> deposits using digitally processed band-selective photographs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ivanov, S. I.; Novikov, V. V.; Popov, A. P.; Tadzhidinov, Kh. G.</p> <p>1989-08-01</p> <p>A procedure is described for the digital processing of band-selective aerial photographs of volcano-bearing surfaces. The brightness and color parameters of samples of <span class="hlt">volcanic</span> rocks and <span class="hlt">soils</span> in their natural bedding are examined, and the results of two-parameter (albedo-color) mapping for an area around the Tolbachin Volcano are discussed. It is shown that the information obtained with this procedure yields accurate predictions of geochemical properties of <span class="hlt">volcanic</span> deposits from optical data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1983/0788/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1983/0788/report.pdf"><span>Cenozoic <span class="hlt">volcanic</span> rocks of Saudi Arabia</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Coleman, R.G.; Gregory, R.T.; Brown, G.F.</p> <p>2016-01-01</p> <p>The historical record of <span class="hlt">volcanic</span> activity in Saudi Arabia suggests that <span class="hlt">volcanism</span> is dormant. The harrats should be evaluated for their potential as <span class="hlt">volcanic</span> hazards and as sources of geothermal energy. The <span class="hlt">volcanic</span> rocks are natural traps for groundwater; thus water resources for agriculture may be significant and should be investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5528677','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5528677"><span>Pulmonary toxicity of Mount St. Helens <span class="hlt">volcanic</span> ash</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sanders, C.L.; Conklin, A.W.; Gelman, R.A.; Adee, R.R.; Rhoads, K.</p> <p>1982-02-01</p> <p>The effects of Mount St. Helens <span class="hlt">volcanic</span> ash, a sandy loam <span class="hlt">soil</span>, and quartz particles on the lung and mediastinal lymph nodes of Fischer rats were studied at time intervals of up to 109 days after in tratracheal instillation of 40 mg ash, <span class="hlt">soil</span>, or quartz in a single dose or after multiple doses of ash instilled in seven consecutive weekly doses for a total deposition of 77 mg. Quartz caused early granuloma formation, later fibrosis was also seen in lymph nodes. <span class="hlt">Volcanic</span> ash caused an ill-defined inflammatory reaction with a few rats showing granuloma formulation, a very limited linear fibrosis, and a moderate lipoproteinosis, and lymph nodes were enlarged with numerous microgranulomas but without reticulin and collagen formation. Pulmonary reactions to <span class="hlt">soil</span> particles were less intense but similar to those in ash- exposed animals; lymph nodes were not enlarged. No significant clearance of ash was found at 3 months after instillation. <span class="hlt">Volcanic</span> ash produced a simple pneumoconiosis similar to what has been described for animals and humans living for prolonged periods of time in dusty desert areas of the United States.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18278024','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18278024"><span>Diffuse <span class="hlt">volcanic</span> emissions of carbon dioxide from Vulcano Island, Italy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Baubron, J C; Allard, P; Toutain, J P</p> <p>1990-03-01</p> <p>RECENT investigations on Mount Etna (Sicily)(1-3) have revealed that volcanoes may release abundant carbon dioxide not only from their active craters, but also from their flanks, as diffuse <span class="hlt">soil</span> emanations. Here we present analyses of <span class="hlt">soil</span> gases and air in water wells on Vulcano Island which provide further evidence of such lateral degassing. Nearly pure carbon dioxide, enriched in helium and radon, escapes from the slopes of the Fossa active cone, adding a total output of 30 tonnes per day to the fumarolic crater discharge ( 180 tonnes CO(2) per day). This emanation has similar He/CO(2) and (13)C/(12)C ratios to those of the crater fumaroles (300%ndash;500 degrees C) and therefore a similar <span class="hlt">volcanic</span> origin. Gases rich in carbon dioxide also escape at sea level along the isthmus between the Fossa and Vulcanello <span class="hlt">volcanic</span> cones, but their depletion in both He and (13)C suggests a distinct source. Diffuse <span class="hlt">volcanic</span> gas emanations, once their genetic link with central fumarole degassing has been demonstrated, can be used for continuous volcano monitoring, at safe distances from active craters. Such monitoring has been initiated at Vulcano, where <span class="hlt">soil</span> and well emanations of nearly pure CO(2) themselves represent a threat to the local population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/journal/1974/vol2issue1/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/journal/1974/vol2issue1/report.pdf"><span>Lunar highlands <span class="hlt">volcanism</span> implications from Luna 20 and Apollo 16</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wilshire, H.G.; Wilhelms, D.E.; Howard, K.A.</p> <p>1974-01-01</p> <p>Highlands materials sampled at the Apollo 16 and Luna 20 sites represent units of distinctive morphology that are widespread on the lunar nearside. Samples from the Apollo 16 site represent hilly and furrowed materials of the Descartes highlands and Cayley Formation. Materials were collected by Luna 20 from terrain resembling the Descartes terrain. Most photogeologic interpretations of these units favored <span class="hlt">volcanic</span> origins, but the samples fail to support this interpretation. Luna 20 <span class="hlt">soil</span> fragments are mainly glassy microbreccia with lithic inclusions of fine-grained hornfels; less than 3 percent of the fragments have textures of <span class="hlt">volcanic</span> rocks, and most of these are likely crystalline products of impact melting. Apollo 16 <span class="hlt">soils</span> formed on ejecta derived from a plutonic anorthosite-norite-troctolite suite. The similarity of Luna 20 <span class="hlt">soils</span> indicates that these too formed as regolith on ejecta of anorthosite-norite-troctolitc composition. Interpretation of the samples from the two locations now suggests that hilly and furrowed terrains, previously thought to be of <span class="hlt">volcanic</span> origin, are impact ejecta; in view of the plutonic nature of the source rocks and their extensive fusion and metamorphism, it is likely that the ejecta were derived from multiring basins. At one point, the Apollo 16 site, the Cayley Formation is composed of basin ejecta.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.B31C0433M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.B31C0433M"><span>Bioindication of <span class="hlt">volcanic</span> mercury (Hg) deposition around Mt Etna (Sicily)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, R.; Witt, M. L.; Sawyer, G. M.; Watt, S.; Bagnato, E.; Calabrese, S.; Aiuppa, A.; Delmelle, P.; Pyle, D. M.; Mather, T. A.</p> <p>2012-12-01</p> <p>Mt. Etna is a major natural source of Hg to the Mediterranean region. Total mercury concentrations, [Hg]tot, in Castanea sativa (sweet chestnut) leaves sampled 7-13 km from Etna's vents (during six campaigns in 2005-2011) were determined using atomic absorption spectroscopy. [Hg]tot in C. sativa was greatest on Etna's SE flank reflecting Hg deposition from the typically overhead <span class="hlt">volcanic</span> plume. When adjusted for leaf age, [Hg]tot in C. sativa also increased with recent eruptive activity. [Hg]tot in C. sativa was not controlled by [Hg]tot in <span class="hlt">soils</span>, which instead was greatest on the (upwind) NW flank and correlated strongly with <span class="hlt">soil</span> organic matter (% Org). Our results suggest that at least ~1% of Hg emitted from Etna is deposited proximally, supporting recent measurement and model results which indicate that GEM (Hg0; the dominant form of Hg in high temperature magmatic gases) is oxidised rapidly to RGM and Hgp in ambient temperature <span class="hlt">volcanic</span> plumes. Samples of C. sativa and <span class="hlt">soils</span> were also collected in July and September 2012 alongside SO2 and acid gas diffusion tube samples. These new samples will enable us to investigate Hg accumulation over a single growth season with reference to the exposure of vegetation to <span class="hlt">volcanic</span> gases and particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://medlineplus.gov/ency/article/007468.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/article/007468.htm"><span>Lung problems and <span class="hlt">volcanic</span> smog</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... smog forms. This smog is a type of air pollution. <span class="hlt">Volcanic</span> smog also contains highly acidic aerosols (tiny ... References Balmes JR, Eisner MD. Indoor and outdoor air pollution. In: Broaddus VC, Mason RJ, Ernst JD, et ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatGe...7...84J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatGe...7...84J"><span>Volcanology: <span class="hlt">Volcanic</span> bipolar disorder explained</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jellinek, Mark</p> <p>2014-02-01</p> <p>Eruptions come in a range of magnitudes. Numerical simulations and laboratory experiments show that rare, giant super-eruptions and smaller, more frequent events reflect a transition in the essential driving forces for <span class="hlt">volcanism</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V44C..05C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V44C..05C"><span>Monogenetic <span class="hlt">volcanic</span> hazards and assessment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Connor, C.; Connor, L. J.; Richardson, J. A.</p> <p>2012-12-01</p> <p>Many of the Earth's major cities are build on the products of monogenetic <span class="hlt">volcanic</span> eruptions and within geologically active basaltic <span class="hlt">volcanic</span> fields. These cities include Mexico City (Mexico), Auckland (New Zealand), Melbourne (Australia), and Portland (USA) to name a few. <span class="hlt">Volcanic</span> hazards in these areas are complex, and involve the potential formation of new <span class="hlt">volcanic</span> vents and associated hazards, such as lava flows, tephra fallout, and ballistic hazards. Hazard assessment is complicated by the low recurrence rate of <span class="hlt">volcanism</span> in most <span class="hlt">volcanic</span> fields. We have developed a two-stage process for probabilistic modeling monogenetic <span class="hlt">volcanic</span> hazards. The first step is an estimation of the possible locations of future eruptive vents based on kernel density estimation and recurrence rate of <span class="hlt">volcanism</span> using Monte Carlo simulation and accounting for uncertainties in age determinations. The second step is convolution of this spatial density / recurrence rate model with hazard codes for modeling lava inundation, tephra fallout, and ballistic impacts. A methodology is presented using this two-stage approach to estimate lava flow hazard in several monogenetic <span class="hlt">volcanic</span> fields, including at a nuclear power plant site near the Shamiram Plateau, a Quaternary <span class="hlt">volcanic</span> field in Armenia. The location of possible future vents is determined by estimating spatial density from a distribution of 18 mapped vents using a 2-D elliptical Gaussian kernel function. The SAMSE method, a modified asymptotic mean squared error approach, uses the distribution of known eruptive vents to optimally determine a smoothing bandwidth for the Gaussian kernel function. The result is a probability map of vent density. A large random sample (N=10000) of vent locations is drawn from this probability map. For each randomly sampled vent location, a lava flow inundation model is executed. Lava flow input parameters (volume and average thickness) are determined from distributions fit to field observations of the low</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017724','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017724"><span><span class="hlt">Volcanic</span> hazards and aviation safety</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Casadevall, Thomas J.; Thompson, Theodore B.; Ewert, John W.; ,</p> <p>1996-01-01</p> <p>An aeronautical chart was developed to determine the relative proximity of volcanoes or ash clouds to the airports and flight corridors that may be affected by <span class="hlt">volcanic</span> debris. The map aims to inform and increase awareness about the close spatial relationship between volcanoes and aviation operations. It shows the locations of the active volcanoes together with selected aeronautical navigation aids and great-circle routes. The map mitigates the threat that <span class="hlt">volcanic</span> hazards pose to aircraft and improves aviation safety.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SPIE.8764E..0LV','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SPIE.8764E..0LV"><span><span class="hlt">Hardening</span> digital systems with distributed functionality: robust networks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vaskova, Anna; Portela-Garcia, Marta; Garcia-Valderas, Mario; López-Ongil, Celia; Portilla, Jorge; Valverde, Juan; de la Torre, Eduardo; Riesgo, Teresa</p> <p>2013-05-01</p> <p>Collaborative <span class="hlt">hardening</span> and hardware redundancy are nowadays the most interesting solutions in terms of fault tolerance achieved and low extra cost imposed to the project budget. Thanks to the powerful and cheap digital devices that are available in the market, extra processing capabilities can be used for redundant tasks, not only in early data processing (sensed data) but also in routing and interfacing1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060039823&hterms=pea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpea','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060039823&hterms=pea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpea"><span>Total dose performance of radiation <span class="hlt">hardened</span> voltage regulators and references</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McClure, S.; Gorelick, J.; Pease, R.; Rax, B.; Ladbury, R.</p> <p>2001-01-01</p> <p>Total dose test of commercially available radiation <span class="hlt">hardened</span> bipolar voltage regulators and references show reduced sensitivity to dose rate and varying sensitivity to bias under pressure. Behavior of critical parameters in different dose rate and bias conditions is compared and the impact to hardness assurance methodology is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6081851','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6081851"><span>A radiation-<span class="hlt">hardened</span> 16/32-bit microprocessor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hass, K.J.; Treece, R.K.; Giddings, A.E.</p> <p>1989-01-01</p> <p>A radiation-<span class="hlt">hardened</span> 16/32-bit microprocessor has been fabricated and tested. Our initial evaluation has demonstrated that it is functional after a total gamma dose of 5Mrad(Si) and is immune to SEU from Krypton ions. 3 refs., 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18517408','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18517408"><span>Strain <span class="hlt">hardening</span> of polymer glasses: entanglements, energetics, and plasticity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoy, Robert S; Robbins, Mark O</p> <p>2008-03-01</p> <p>Simulations are used to examine the microscopic origins of strain <span class="hlt">hardening</span> in polymer glasses. While stress-strain curves for a wide range of temperature can be fit to the functional form predicted by entropic network models, many other results are fundamentally inconsistent with the physical picture underlying these models. Stresses are too large to be entropic and have the wrong trend with temperature. The most dramatic <span class="hlt">hardening</span> at large strains reflects increases in energy as chains are pulled taut between entanglements rather than a change in entropy. A weak entropic stress is only observed in shape recovery of deformed samples when heated above the glass transition. While short chains do not form an entangled network, they exhibit partial shape recovery, orientation, and strain <span class="hlt">hardening</span>. Stresses for all chain lengths collapse when plotted against a microscopic measure of chain stretching rather than the macroscopic stretch. The thermal contribution to the stress is directly proportional to the rate of plasticity as measured by breaking and reforming of interchain bonds. These observations suggest that the correct microscopic theory of strain <span class="hlt">hardening</span> should be based on glassy state physics rather than rubber elasticity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/3357','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/3357"><span>BUSFET - A Novel Radiation-<span class="hlt">Hardened</span> SOI Transistor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dodd, P.E.; Draper, B.L.; Schwank, J.R.; Shaneyfelt, M.R.</p> <p>1999-02-04</p> <p>A partially-depleted SOI transistor structure has been designed that does not require the use of specially-processed <span class="hlt">hardened</span> buried oxides for total-dose hardness and maintains the intrinsic SEU and dose rate hardness advantages of SOI technology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('//www.loc.gov/pictures/collection/hh/item/wv0329.photos.167653p/','SCIGOV-HHH'); return false;" href="//www.loc.gov/pictures/collection/hh/item/wv0329.photos.167653p/"><span>49. INTERIOR VIEW OF <span class="hlt">HARDENER</span> AREA SHOWING GAUGE THAT MEASURES ...</span></a></p> <p><a target="_blank" href="http://www.loc.gov/pictures/collection/hh/">Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey</a></p> <p></p> <p></p> <p>49. INTERIOR VIEW OF <span class="hlt">HARDENER</span> AREA SHOWING GAUGE THAT MEASURES HARDNESS, THE NAIL MUST BREAK IN THE CENTER RANGE OF THE CURVED BAR TO HAVE THE CORRECT HARDNESS (THE NAIL WILL BREAK TOO EASILY IF TOO HARD AND WILL BEND TOO MUCH IF TOO SOFT) - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26659554','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26659554"><span>Iterative Beam <span class="hlt">Hardening</span> Correction for Multi-Material Objects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Yunsong; Li, Mengfei</p> <p>2015-01-01</p> <p>In this paper, we propose an iterative beam <span class="hlt">hardening</span> correction method that is applicable for the case with multiple materials. By assuming that the materials composing scanned object are known and that they are distinguishable by their linear attenuation coefficients at some given energy, the beam <span class="hlt">hardening</span> correction problem is converted into a nonlinear system problem, which is then solved iteratively. The reconstructed image is the distribution of linear attenuation coefficient of the scanned object at a given energy. So there are no beam <span class="hlt">hardening</span> artifacts in the image theoretically. The proposed iterative scheme combines an accurate polychromatic forward projection with a linearized backprojection. Both forward projection and backprojection have high degree of parallelism, and are suitable for acceleration on parallel systems. Numerical experiments with both simulated data and real data verifies the validity of the proposed method. The beam <span class="hlt">hardening</span> artifacts are alleviated effectively. In addition, the proposed method has a good tolerance on the error of the estimated x-ray spectrum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011MSHT...53..318G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011MSHT...53..318G"><span>Surface <span class="hlt">hardening</span> of parts from ferrite-pearlite gray iron</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gurevich, Yu. G.; Ovsyannikov, V. E.; Marfitsyn, V. V.; Frolov, V. A.</p> <p>2011-10-01</p> <p>The possibility of a simple method of chromizing of parts from ferrite-pearlite gray iron is studied theoretically and proved experimentally. A process for diffusion chromizing of parts from this iron is suggested. When followed by surface <span class="hlt">hardening</span> the process yields a high-hardness surface layer with abrasive strength comparable to that of white chromium cast iron.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20657044','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20657044"><span><span class="hlt">Hardening</span> by twin boundary during nanoindentation in nanocrystals.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qu, Shaoxing; Zhou, Haofei</p> <p>2010-08-20</p> <p>The atomistic deformation processes of nanocrystals embedded with nanoscale twin boundaries during nanoindentation are studied by molecular dynamics simulations. Load-displacement curves are obtained and the <span class="hlt">hardening</span> mechanisms associated with the nanoscale twin boundaries are revealed. Johnson's theoretical indentation model is adopted to estimate the elastic stage of the nanoindentation. In addition, twin boundary-mediated dislocation nucleation is observed and analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9413E..1YL','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9413E..1YL"><span>Beam <span class="hlt">hardening</span> correction for sparse-view CT reconstruction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Wenlei; Rong, Junyan; Gao, Peng; Liao, Qimei; Lu, HongBing</p> <p>2015-03-01</p> <p>Beam <span class="hlt">hardening</span>, which is caused by spectrum polychromatism of the X-ray beam, may result in various artifacts in the reconstructed image and degrade image quality. The artifacts would be further aggravated for the sparse-view reconstruction due to insufficient sampling data. Considering the advantages of the total-variation (TV) minimization in CT reconstruction with sparse-view data, in this paper, we propose a beam <span class="hlt">hardening</span> correction method for sparse-view CT reconstruction based on Brabant's modeling. In this correction model for beam <span class="hlt">hardening</span>, the attenuation coefficient of each voxel at the effective energy is modeled and estimated linearly, and can be applied in an iterative framework, such as simultaneous algebraic reconstruction technique (SART). By integrating the correction model into the forward projector of the algebraic reconstruction technique (ART), the TV minimization can recover images when only a limited number of projections are available. The proposed method does not need prior information about the beam spectrum. Preliminary validation using Monte Carlo simulations indicates that the proposed method can provide better reconstructed images from sparse-view projection data, with effective suppression of artifacts caused by beam <span class="hlt">hardening</span>. With appropriate modeling of other degrading effects such as photon scattering, the proposed framework may provide a new way for low-dose CT imaging.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA613435','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA613435"><span>Linear Friction Welding Process Model for Carpenter Custom 465 Precipitation-<span class="hlt">Hardened</span> Martensitic Stainless Steel</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2014-04-11</p> <p>Carpenter Custom 465 precipitation-<span class="hlt">hardened</span> martensitic stainless steel to develop a linear friction welding (LFW) process model for this material...Model for Carpenter Custom 465 Precipitation-<span class="hlt">Hardened</span> Martensitic Stainless Steel The views, opinions and/or findings contained in this report are...Carpenter Custom 465 precipitation-<span class="hlt">hardened</span> martensiticstainless steel , linear friction welding, process modeling REPORT DOCUMENTATION PAGE 11</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22675161','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22675161"><span>Nanoscale characterization of the biomechanical <span class="hlt">hardening</span> of bovine zona pellucida.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boccaccio, Antonio; Frassanito, Maria Cristina; Lamberti, Luciano; Brunelli, Roberto; Maulucci, Giuseppe; Monaci, Maurizio; Papi, Massimiliano; Pappalettere, Carmine; Parasassi, Tiziana; Sylla, Lakamy; Ursini, Fulvio; De Spirito, Marco</p> <p>2012-11-07</p> <p>The zona pellucida (ZP) is an extracellular membrane surrounding mammalian oocytes. The so-called zona <span class="hlt">hardening</span> plays a key role in fertilization process, as it blocks polyspermy, which may also be caused by an increase in the mechanical stiffness of the ZP membrane. However, structural reorganization mechanisms leading to ZP's biomechanical <span class="hlt">hardening</span> are not fully understood yet. Furthermore, a correct estimate of the elastic properties of the ZP is still lacking. Therefore, the aim of the present study was to investigate the biomechanical behaviour of ZP membranes extracted from mature and fertilized bovine oocytes to better understand the mechanisms involved in the structural reorganization of the ZP that may lead to the biomechanical <span class="hlt">hardening</span> of the ZP. For that purpose, a hybrid procedure is developed by combining atomic force microscopy nanoindentation measurements, nonlinear finite element analysis and nonlinear optimization. The proposed approach allows us to determine the biomechanical properties of the ZP more realistically than the classical analysis based on Hertz's contact theory, as it accounts for the nonlinearity of finite indentation process, hyperelastic behaviour and material heterogeneity. Experimental results show the presence of significant biomechanical <span class="hlt">hardening</span> induced by the fertilization process. By comparing various hyperelastic constitutive models, it is found that the Arruda-Boyce eight-chain model best describes the biomechanical response of the ZP. Fertilization leads to an increase in the degree of heterogeneity of membrane elastic properties. The Young modulus changes sharply within a superficial layer whose thickness is related to the characteristic distance between cross-links in the ZP filamentous network. These findings support the hypothesis that biomechanical <span class="hlt">hardening</span> of bovine ZP is caused by an increase in the number of inter-filaments cross-links whose density should be higher in the ZP inner side.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS11E..06S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS11E..06S"><span>Are Axial <span class="hlt">Volcanic</span> Ridges where all the (<span class="hlt">volcanic</span>) action is?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Searle, R. C.</p> <p>2012-12-01</p> <p>Although axial <span class="hlt">volcanic</span> ridges (AVRs) are generally recognised as the main loci for lithospheric generation at slow-spreading mid-ocean ridges, various recent studies have suggested that axial <span class="hlt">volcanism</span> is not confined to them. Here I present evidence from three studies for significant amounts of off-AVR <span class="hlt">volcanism</span> at three slow-spreading ridges. 1) Near-bottom side-scan sonar (TOBI) images of the Mid-Atlantic Ridge near 13°N show a complex pattern of closely-spaced, active oceanic core complexes (OCCs) where plate separation is largely a-<span class="hlt">volcanic</span>, separated by short segments of vigorous <span class="hlt">volcanic</span> spreading. In one such <span class="hlt">volcanic</span> segment, the brightest sea floor and therefore inferred youngest <span class="hlt">volcanism</span> occurs not on the topographic axis (an apparently 'old' AVR) but at the edge of a broad axial valley. 2) A similar TOBI survey of the Mid-Cayman Spreading Centre reveals AVRs in the north and south flanking an OCC (Mt. Dent) and a non-<span class="hlt">volcanic</span> ridge interpreted as tectonically extruded peridotite ('smooth' sea floor). In both AVR segments there are clear, young lava flows that have erupted from perched sources part way up the median valley walls and have partly flowed down into the valley. 3) The third case is from the Mid-Atlantic Ridge at 45°N, where we conducted a detailed geophysical and geological study of an AVR and surrounding median valley floor. The AVR is largely surrounded by flat sea floor composed mainly of lobate and sheet flows, whereas the AVR comprises predominantly pillow lavas. Although we have no firm dates, various indicators suggest most lavas on the AVR are around 10ka old or somewhat less. The apparently youngest (brightest acoustic returns, thinnest sediment cover) of the flat-lying lava flows appears to have a similar age from its degree of sediment cover. Contact relations between these lavas and the AVR flanks show no evidence of a clear age difference between the two, and we think both types of eruption may have occurred roughly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015881','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015881"><span>Age and progression of <span class="hlt">volcanism</span>, Wrangell <span class="hlt">volcanic</span> field, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Richter, D.H.; Smith, James G.; Lanphere, M.A.; Dalrymple, G.B.; Reed, B.L.; Shew, N.</p> <p>1990-01-01</p> <p>The Wrangell <span class="hlt">volcanic</span> field covers more than 10 000 km2 in southern Alaska and extends uninterrupted into northwest. Yukon Territory. Lavas in the field exhibit medium-K, calc-alkaline affinities, typical of continental <span class="hlt">volcanic</span> arcs along convergent plate margins. Eleven major eruptive centers are recognized in the Alaskan part of the field. More than 90 K-Ar age determinations in the field show a northwesterly progression of eruptive activity from 26 Ma, near the Alaska-Yukon border, to about 0.2 Ma at the northwest end of the field. A few age determinations in the southeast extension of the field in Yukon Territory, Canada, range from 11 to 25 Ma. The ages indicate that the progression of <span class="hlt">volcanism</span> in the Alaska part of the field increased from about 0.8 km/Ma, at 25 Ma, to more than 20 km/MA during the past 2 Ma. The progression of <span class="hlt">volcanic</span> activity and its increased rate of migration with time is attributed to changes in the rate and angle of Pacific plate convergence and the progressive decoupling of the Yakutat terrane from North America. Subduction of Yakutat terrane-Pacific plate and Wrangell <span class="hlt">volcanic</span> activity ceased about 200 000 years age when Pacific plate motion was taken up by strike-slip faulting and thrusting. ?? 1990 Springer-Verlag.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1613533P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1613533P"><span>Geochemical Interpretation of Collision <span class="hlt">Volcanism</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pearce, Julian</p> <p>2014-05-01</p> <p>Collision <span class="hlt">volcanism</span> can be defined as <span class="hlt">volcanism</span> that takes place during an orogeny from the moment that continental subduction starts to the end of orogenic collapse. Its importance in the Geological Record is greatly underestimated as collision <span class="hlt">volcanics</span> are easily misinterpreted as being of <span class="hlt">volcanic</span> arc, extensional or mantle plume origin. There are many types of collision <span class="hlt">volcanic</span> province: continent-island arc collision (e.g. Banda arc); continent-active margin collision (e.g. Tibet, Turkey-Iran); continent-rear-arc collision (e.g. Bolivia); continent-continent collision (e.g. Tuscany); and island arc-island arc collision (e.g. Taiwan). Superimposed on this variability is the fact that every orogeny is different in detail. Nonetheless, there is a general theme of cyclicity on different time scales. This starts with syn-collision <span class="hlt">volcanism</span> resulting from the subduction of an ocean-continent transition and continental lithosphere, and continues through post-collision <span class="hlt">volcanism</span>. The latter can be subdivided into orogenic <span class="hlt">volcanism</span>, which is related to thickened crust, and post-orogenic, which is related to orogenic collapse. Typically, but not always, collision <span class="hlt">volcanism</span> is preceded by normal arc <span class="hlt">volcanism</span> and followed by normal intraplate <span class="hlt">volcanism</span>. Identification and interpretation of collision <span class="hlt">volcanism</span> in the Geologic Record is greatly facilitated if a dated stratigraphic sequence is present so that the petrogenic evolution can be traced. In any case, the basis of fingerprinting collision terranes is to use geochemical proxies for mantle and subduction fluxes, slab temperatures, and depths and degrees of melting. For example, syn-collision <span class="hlt">volcanism</span> is characterized by a high subduction flux relative to mantle flux because of the high input flux of fusible sediment and crust coupled with limited mantle flow, and because of high slab temperatures resulting from the decrease in subduction rate. The resulting geochemical patterns are similar regardless of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20368458','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20368458"><span>Atmospheric chemistry in <span class="hlt">volcanic</span> plumes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>von Glasow, Roland</p> <p>2010-04-13</p> <p>Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of <span class="hlt">volcanic</span> plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the <span class="hlt">volcanic</span> plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the <span class="hlt">volcanic</span> plume. This would imply an increased lifetime of methane in <span class="hlt">volcanic</span> plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of <span class="hlt">volcanic</span> mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910012330','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910012330"><span>Climatic impact of <span class="hlt">volcanic</span> eruptions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rampino, Michael R.</p> <p>1991-01-01</p> <p>Studies have attempted to 'isolate' the <span class="hlt">volcanic</span> signal in noisy temperature data. This assumes that it is possible to isolate a distinct <span class="hlt">volcanic</span> signal in a record that may have a combination of forcings (ENSO, solar variability, random fluctuations, <span class="hlt">volcanism</span>) that all interact. The key to discovering the greatest effects of volcanoes on short-term climate may be to concentrate on temperatures in regions where the effects of aerosol clouds may be amplified by perturbed atmospheric circulation patterns. This is especially true in subpolar and midlatitude areas affected by changes in the position of the polar front. Such climatic perturbation can be detected in proxy evidence such as decrease in tree-ring widths and frost rings, changes in the treeline, weather anomalies, severity of sea-ice in polar and subpolar regions, and poor grain yields and crop failures. In low latitudes, sudden temperature drops were correlated with the passage overhead of the <span class="hlt">volcanic</span> dust cloud (Stothers, 1984). For some eruptions, such as Tambora, 1815, these kinds of proxy and anectdotal information were summarized in great detail in a number of papers and books (e.g., Post, 1978; Stothers, 1984; Stommel and Stommel, 1986; C. R. Harrington, in press). These studies lead to the general conclusion that regional effects on climate, sometimes quite severe, may be the major impact of large historical <span class="hlt">volcanic</span> aerosol clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20473490','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20473490"><span>Bacterial diversity of weathered terrestrial Icelandic <span class="hlt">volcanic</span> glasses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kelly, Laura C; Cockell, Charles S; Piceno, Yvette M; Andersen, Gary L; Thorsteinsson, Thorsteinn; Marteinsson, Viggo</p> <p>2010-11-01</p> <p>The diversity of microbial communities inhabiting two terrestrial <span class="hlt">volcanic</span> glasses of contrasting mineralogy and age was characterised. Basaltic glass from a <0.8 Ma hyaloclastite deposit (Valafell) harboured a more diverse Bacteria community than the younger rhyolitic glass from ∼150-300 AD (Dόmadalshraun lava flow). Actinobacteria dominated 16S rRNA gene clone libraries from both sites, however, Proteobacteria, Acidobacteria and Cyanobacteria were also numerically abundant in each. A significant proportion (15-34%) of the sequenced clones displayed <85% sequence similarities with current database sequences, thus suggesting the presence of novel microbial diversity in each <span class="hlt">volcanic</span> glass. The majority of clone sequences shared the greatest similarity to uncultured organisms, mainly from <span class="hlt">soil</span> environments, among these clones from Antarctic environments and Hawaiian and Andean <span class="hlt">volcanic</span> deposits. Additionally, a large number of clones within the Cyanobacteria and Proteobacteria were more similar to sequences from other lithic environments, included among these Icelandic clones from crystalline basalt and rhyolite, however, no similarities to sequences reported from marine <span class="hlt">volcanic</span> glasses were observed. PhyloChip analysis detected substantially greater numbers of phylotypes at both sites than the corresponding clone libraries, but nonetheless also identified the basaltic glass community as the richer, containing approximately 29% unique phylotypes compared to rhyolitic glass.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001eso..presP..21.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001eso..presP..21."><span>Aurorae and <span class="hlt">Volcanic</span> Eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p>2001-06-01</p> <p>Thermal-IR Observations of Jupiter and Io with ISAAC at the VLT Summary Impressive thermal-infrared images have been obtained of the giant planet Jupiter during tests of a new detector in the ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). . They show in particular the full extent of the northern auroral ring and part of the southern aurora. A <span class="hlt">volcanic</span> eruption was also imaged on Io , the very active inner Jovian moon. Although these observations are of an experimental nature, they demonstrate a great potential for regular monitoring of the Jovian magnetosphere by ground-based telescopes together with space-based facilities. They also provide the added benefit of direct comparison with the terrestrial magnetosphere. PR Photo 21a/01 : ISAAC image of Jupiter (L-band: 3.5-4.0 µm) . PR Photo 21b/01 : ISAAC image of Jupiter (Narrow-band 4.07 µm) . PR Photo 21c/01 : ISAAC image of Jupiter (Narrow-band 3.28 µm) . PR Photo 21d/01 : ISAAC image of Jupiter (Narrow-band 3.21 µm) . PR Photo 21e/01 : ISAAC image of the Jovian aurorae (false-colour). PR Photo 21f/01 : ISAAC image of <span class="hlt">volcanic</span> activity on Io . Addendum : The Jovian aurorae and polar haze. Aladdin Meets Jupiter Thermal-infrared images of Jupiter and its <span class="hlt">volcanic</span> moon Io have been obtained during a series of system tests with the new Aladdin detector in the Infrared Spectrometer And Array Camera (ISAAC) , in combination with an upgrade of the ESO-developed detector control electronics IRACE. This state-of-the-art instrument is attached to the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory. The observations were made on November 14, 2000, through various filters that isolate selected wavebands in the thermal-infrared spectral region [1]. They include a broad-band L-filter (wavelength interval 3.5 - 4.0 µm) as well as several narrow-band filters (3.21, 3.28 and 4.07 µm). The filters allow to record the light from different components of the Jovian atmosphere</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EOSTr..93U.104B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93U.104B"><span>Io's <span class="hlt">volcanism</span> influences Jupiter's magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balcerak, Ernie</p> <p>2012-02-01</p> <p><span class="hlt">Volcanic</span> emissions from Jupiter's moon Io supply plasma to the planet's magnetosphere and lead to its main auroral emissions. New observations show that the main auroral oval expanded and outer emissions brightened in spring 2007. Some studies have suggested that magnetospheric changes such as these could be caused by changes in the incoming solar wind. Bonfond et al. present several lines of evidence—including images from the Hubble Space Telescope and observations of a <span class="hlt">volcanic</span> plume on Io from the New Horizons probe along with measurements of increased emissions from Jupiter's sodium cloud—that indicate that Io's <span class="hlt">volcanism</span> controls changes in Jupiter's magnetosphere. (Geophysical Research Letters, doi:10.1029/2011GL050253, 2012)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10146200','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10146200"><span>Models of <span class="hlt">volcanic</span> eruption hazards</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wohletz, K.H.</p> <p>1992-06-01</p> <p><span class="hlt">Volcanic</span> eruptions pose an ever present but poorly constrained hazard to life and property for geothermal installations in <span class="hlt">volcanic</span> areas. Because eruptions occur sporadically and may limit field access, quantitative and systematic field studies of eruptions are difficult to complete. Circumventing this difficulty, laboratory models and numerical simulations are pivotal in building our understanding of eruptions. For example, the results of fuel-coolant interaction experiments show that magma-water interaction controls many eruption styles. Applying these results, increasing numbers of field studies now document and interpret the role of external water eruptions. Similarly, numerical simulations solve the fundamental physics of high-speed fluid flow and give quantitative predictions that elucidate the complexities of pyroclastic flows and surges. A primary goal of these models is to guide geologists in searching for critical field relationships and making their interpretations. Coupled with field work, modeling is beginning to allow more quantitative and predictive <span class="hlt">volcanic</span> hazard assessments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900033508&hterms=Volcanic+Eruptions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DVolcanic%2BEruptions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900033508&hterms=Volcanic+Eruptions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DVolcanic%2BEruptions"><span><span class="hlt">Volcanic</span> eruptions and solar activity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stothers, Richard B.</p> <p>1989-01-01</p> <p>The historical record of large <span class="hlt">volcanic</span> eruptions from 1500 to 1980 is subjected to detailed time series analysis. In two weak but probably statistically significant periodicities of about 11 and 80 yr, the frequency of <span class="hlt">volcanic</span> eruptions increases (decreases) slightly around the times of solar minimum (maximum). Time series analysis of the volcanogenic acidities in a deep ice core from Greenland reveals several very long periods ranging from about 80 to about 350 yr which are similar to the very slow solar cycles previously detected in auroral and C-14 records. Solar flares may cause changes in atmospheric circulation patterns that abruptly alter the earth's spin. The resulting jolt probably triggers small earthquakes which affect <span class="hlt">volcanism</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7051624','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7051624"><span>Models of <span class="hlt">volcanic</span> eruption hazards</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wohletz, K.H.</p> <p>1992-01-01</p> <p><span class="hlt">Volcanic</span> eruptions pose an ever present but poorly constrained hazard to life and property for geothermal installations in <span class="hlt">volcanic</span> areas. Because eruptions occur sporadically and may limit field access, quantitative and systematic field studies of eruptions are difficult to complete. Circumventing this difficulty, laboratory models and numerical simulations are pivotal in building our understanding of eruptions. For example, the results of fuel-coolant interaction experiments show that magma-water interaction controls many eruption styles. Applying these results, increasing numbers of field studies now document and interpret the role of external water eruptions. Similarly, numerical simulations solve the fundamental physics of high-speed fluid flow and give quantitative predictions that elucidate the complexities of pyroclastic flows and surges. A primary goal of these models is to guide geologists in searching for critical field relationships and making their interpretations. Coupled with field work, modeling is beginning to allow more quantitative and predictive <span class="hlt">volcanic</span> hazard assessments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25965858','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25965858"><span>Strain <span class="hlt">Hardening</span> and Size Effect in Five-fold Twinned Ag Nanowires.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Narayanan, Sankar; Cheng, Guangming; Zeng, Zhi; Zhu, Yong; Zhu, Ting</p> <p>2015-06-10</p> <p>Metallic nanowires usually exhibit ultrahigh strength but low tensile ductility owing to their limited strain <span class="hlt">hardening</span> capability. Here we study the unique strain <span class="hlt">hardening</span> behavior of the five-fold twinned Ag nanowires by nanomechanical testing and atomistic modeling. In situ tensile tests within a scanning electron microscope revealed strong strain <span class="hlt">hardening</span> behavior of the five-fold twinned Ag nanowires. Molecular dynamics simulations showed that such strain <span class="hlt">hardening</span> was critically controlled by twin boundaries and pre-existing defects. Strain <span class="hlt">hardening</span> was size dependent; thinner nanowires achieved more <span class="hlt">hardening</span> and higher ductility. The size-dependent strain <span class="hlt">hardening</span> was found to be caused by the obstruction of surface-nucleated dislocations by twin boundaries. Our work provides mechanistic insights into enhancing the tensile ductility of metallic nanostructures by engineering the internal interfaces and defects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/870092','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/870092"><span>Surface <span class="hlt">hardening</span> of titanium alloys with melting depth controlled by heat sink</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Oden, Laurance L.; Turner, Paul C.</p> <p>1995-01-01</p> <p>A process for forming a hard surface coating on titanium alloys includes providing a piece of material containing titanium having at least a portion of one surface to be <span class="hlt">hardened</span>. The piece having a portion of a surface to be <span class="hlt">hardened</span> is contacted on the backside by a suitable heat sink such that the melting depth of said surface to be <span class="hlt">hardened</span> may be controlled. A <span class="hlt">hardening</span> material is then deposited as a slurry. Alternate methods of deposition include flame, arc, or plasma spraying, electrodeposition, vapor deposition, or any other deposition method known by those skilled in the art. The surface to be <span class="hlt">hardened</span> is then selectively melted to the desired depth, dependent on the desired coating thickness, such that a molten pool is formed of the piece surface and the deposited <span class="hlt">hardening</span> material. Upon cooling a <span class="hlt">hardened</span> surface is formed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090032092','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090032092"><span>Using <span class="hlt">Volcanic</span> Ash to Remove Dissolved Uranium and Lead</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McKay, David S.; Cuero, Raul G.</p> <p>2009-01-01</p> <p>Experiments have shown that significant fractions of uranium, lead, and possibly other toxic and/or radioactive substances can be removed from an aqueous solution by simply exposing the solution, at ambient temperature, to a treatment medium that includes weathered <span class="hlt">volcanic</span> ash from Pu'u Nene, which is a cinder cone on the Island of Hawaii. Heretofore, this specific <span class="hlt">volcanic</span> ash has been used for an entirely different purpose: simulating the spectral properties of Martian <span class="hlt">soil</span>. The treatment medium can consist of the <span class="hlt">volcanic</span> ash alone or in combination with chitosan, which is a natural polymer that can be produced from seafood waste or easily extracted from fungi, some bacteria, and some algae. The medium is harmless to plants and animals and, because of the abundance and natural origin of its ingredient( s), is inexpensive. The medium can be used in a variety of ways and settings: it can be incorporated into water-filtration systems; placed in contact or mixed with water-containing solids (e.g., <span class="hlt">soils</span> and sludges); immersed in bodies of water (e.g., reservoirs, lakes, rivers, or wells); or placed in and around nuclear power plants, mines, and farm fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26301247','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26301247"><span>Air Pollution by Hydrothermal <span class="hlt">Volcanism</span> and Human Pulmonary Function.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Linhares, Diana; Ventura Garcia, Patrícia; Viveiros, Fátima; Ferreira, Teresa; dos Santos Rodrigues, Armindo</p> <p>2015-01-01</p> <p>The aim of this study was to assess whether chronic exposure to volcanogenic air pollution by hydrothermal <span class="hlt">soil</span> diffuse degassing is associated with respiratory defects in humans. This study was carried in the archipelago of the Azores, an area with active <span class="hlt">volcanism</span> located in the Atlantic Ocean where Eurasian, African, and American lithospheric plates meet. A cross-sectional study was performed on a study group of 146 individuals inhabiting an area where <span class="hlt">volcanic</span> activity is marked by active fumarolic fields and <span class="hlt">soil</span> degassing (hydrothermal area) and a reference group of 359 individuals inhabiting an area without these secondary manifestations of <span class="hlt">volcanism</span> (nonhydrothermal area). Odds ratio (OR) and 95% confidence intervals (CIs) were adjusted for age, gender, fatigue, asthma, and smoking. The OR for restrictive defects and for exacerbation of obstructive defects (COPD) in the hydrothermal area was 4.4 (95% CI 1.78-10.69) and 3.2 (95% CI 1.82-5.58), respectively. Increased prevalence of restrictions and all COPD severity ranks (mild, moderate, and severe) was observed in the population from the hydrothermal area. These findings may assist health officials in advising and keeping up with these populations to prevent and minimize the risk of respiratory diseases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4537725','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4537725"><span>Air Pollution by Hydrothermal <span class="hlt">Volcanism</span> and Human Pulmonary Function</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Linhares, Diana; Garcia, Patrícia Ventura; Viveiros, Fátima; Ferreira, Teresa; Rodrigues, Armindo dos Santos</p> <p>2015-01-01</p> <p>The aim of this study was to assess whether chronic exposure to volcanogenic air pollution by hydrothermal <span class="hlt">soil</span> diffuse degassing is associated with respiratory defects in humans. This study was carried in the archipelago of the Azores, an area with active <span class="hlt">volcanism</span> located in the Atlantic Ocean where Eurasian, African, and American lithospheric plates meet. A cross-sectional study was performed on a study group of 146 individuals inhabiting an area where <span class="hlt">volcanic</span> activity is marked by active fumarolic fields and <span class="hlt">soil</span> degassing (hydrothermal area) and a reference group of 359 individuals inhabiting an area without these secondary manifestations of <span class="hlt">volcanism</span> (nonhydrothermal area). Odds ratio (OR) and 95% confidence intervals (CIs) were adjusted for age, gender, fatigue, asthma, and smoking. The OR for restrictive defects and for exacerbation of obstructive defects (COPD) in the hydrothermal area was 4.4 (95% CI 1.78–10.69) and 3.2 (95% CI 1.82–5.58), respectively. Increased prevalence of restrictions and all COPD severity ranks (mild, moderate, and severe) was observed in the population from the hydrothermal area. These findings may assist health officials in advising and keeping up with these populations to prevent and minimize the risk of respiratory diseases. PMID:26301247</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720055070&hterms=Bellcomm&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBellcomm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720055070&hterms=Bellcomm&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBellcomm"><span>Orbital search for lunar <span class="hlt">volcanism</span>.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hodges, R. R., Jr.; Hoffman, J. H.; Yeh, T. T. J.; Chang, G. K.</p> <p>1972-01-01</p> <p>The total rate of <span class="hlt">volcanic</span> release of gases into the lunar atmosphere is estimated to be less than 60 g/sec. One of the implications of this degassing is that, if it occurs as sporadic releases of large quantities of gas, these events can be detected by an orbiting mass spectrometer, such as that carried on the flight of Apollo 15 and one that will operate during the Apollo 16 mission. The nature of a <span class="hlt">volcanic</span> perturbation of the lunar atmosphere is discussed, and a lower bound is derived for the expected time between detected events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1411493S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1411493S"><span>Testing hypotheses for the use of Icelandic <span class="hlt">volcanic</span> ashes as low cost, natural fertilizers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seward, W.; Edwards, B.</p> <p>2012-04-01</p> <p>Andisols are <span class="hlt">soils</span> derived from tephra/<span class="hlt">volcanic</span> bedrock and are generally considered to be fertile for plant growth (cf. University of Hawaii at Manoa, CTAHR). However, few studies have been published examining the immediate effects of the addition of <span class="hlt">volcanic</span> ash to <span class="hlt">soils</span> immediately after an eruption. Our research is motivated by unpublished accounts from Icelandic farmers that the growing season following the 2010 Eyjafjallajökull eruption ended with unusually high yields in areas that were covered by ash from the eruption early in the spring. To test the hypothesis that addition of <span class="hlt">volcanic</span> ash to <span class="hlt">soil</span> would have no immediate effect on plant growth, we conducted a ~6 week growth experiment in at controlled environment at the Dickinson College Farm. The experiment used relatively fast growing grain seeds as a test crop, controlled watering, known quantities of peat as an organic base, and the following general experimental design: peat was mixed in known but systematically differing proportions with 1) commercial quartz sand, 2) basaltic ash from the 2004 Grimsvötn eruption, and 3) trachyandesite ash from the 2010 Eyjafjallajökull eruption. For all experiments, the seeds growing in the simulated <span class="hlt">soil</span> created with the two different composition <span class="hlt">volcanic</span> ash had higher germination rates, higher growth rates, and produced plants that were healthier in appearance than the <span class="hlt">soil</span> made from peat mixed with quartz sand. Some differences were also noted between the germination and grow rates between the basaltic and trachyandesitic ash experiments as well. Working hypotheses to explain these results include (1) shard shapes and vesicles from <span class="hlt">volcanic</span> ash provide better water retention than quartz, allowing water to be stored longer and increasing average <span class="hlt">soil</span> moisture, and (2) chemical nutrients from the ash facilitate germination and growth of plants. Documenting the potential benefits of fresh <span class="hlt">volcanic</span> ash as a fertilizer is important as use of fresh ash fertlizer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/2453','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/2453"><span>A Brief Discussion of Radiation <span class="hlt">Hardening</span> of CMOS Microelectronics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Myers, D.R.</p> <p>1998-12-18</p> <p>Commercial microchips work well in their intended environments. However, generic microchips will not fimction correctly if exposed to sufficient amounts of ionizing radiation, the kind that satellites encounter in outer space. Modern CMOS circuits must overcome three specific concerns from ionizing radiation: total-dose, single-event, and dose-rate effects. Minority-carrier devices such as bipolar transistors, optical receivers, and solar cells must also deal with recombination-generation centers caused by displacement damage, which are not major concerns for majority-carrier CMOS devices. There are ways to make the chips themselves more resistant to radiation. This extra protection, called radiation <span class="hlt">hardening</span>, has been called both a science and an art. Radiation <span class="hlt">hardening</span> requires both changing the designs of the chips and altering the ways that the chips are manufactured.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12502042','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12502042"><span>An energy-based beam <span class="hlt">hardening</span> model in tomography.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van de Casteele, E; Van Dyck, D; Sijbers, J; Raman, E</p> <p>2002-12-07</p> <p>As a consequence of the polychromatic x-ray source, used in micro-computer tomography (microCT) and in medical CT, the attenuation is no longer a linear function of absorber thickness. If this nonlinear beam <span class="hlt">hardening</span> effect is not compensated, the reconstructed images will be corrupted by cupping artefacts. In this paper, a bimodal energy model for the detected energy spectrum is presented, which can be used for reduction of artefacts caused by beam <span class="hlt">hardening</span> in well-specified conditions. Based on the combination of the spectrum of the source and the detector efficiency, the assumption is made that there are two dominant energies which can describe the system. The validity of the proposed model is examined by fitting the model to the experimental datapoints obtained on a microtomograph for different materials and source voltages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JOM....60l..22T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JOM....60l..22T"><span>Transformation <span class="hlt">hardening</span> of steel sheet for automotive applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takechi, H.</p> <p>2008-12-01</p> <p>Among high-strength steels, transformation <span class="hlt">hardening</span> steels such as dual-phase (DP) steel and transformation-induced plasticity (TRIP) steel offer a superior relationship between tensile strength (TS) and elongation (El) on a commercial scale. As demand has grown for lighter-weight automobiles, so also has the demand for higher TS, lower yield ratio, and higher hole expansion ratio grown. Recently DP steel has been developed with precipitation <span class="hlt">hardening</span> and grain refining by TiC. A new TRIP steel composed of 5Mn-2Si and control-rolled with niobium addition suggests the formation of retained austenite ( γ R ) as much as 30% and TS × El = 3,000 kgf/mm2·%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720010013','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720010013"><span><span class="hlt">Hardening</span> electronic devices against very high total dose radiation environments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Buchanan, B.; Shedd, W.; Roosild, S.; Dolan, R.</p> <p>1972-01-01</p> <p>The possibilities and limitations of <span class="hlt">hardening</span> silicon semiconductor devices to the high neutron and gamma radiation levels and greater than 10 to the eighth power rads required for the NERVA nuclear engine development are discussed. A comparison is made of the high dose neutron and gamma <span class="hlt">hardening</span> potential of bipolar, metal insulator semiconductors and junction field effect transistors. Experimental data is presented on device degradation for the high neutron and gamma doses. Previous data and comparisons indicate that the JFET is much more immune to the combined neutron displacement and gamma ionizing effects than other transistor types. Experimental evidence is also presented which indicates that p channel MOS devices may be able to meet the requirements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22413445','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22413445"><span>Segmentation-free empirical beam <span class="hlt">hardening</span> correction for CT</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schüller, Sören; Sawall, Stefan; Stannigel, Kai; Hülsbusch, Markus; Ulrici, Johannes; Hell, Erich; Kachelrieß, Marc</p> <p>2015-02-15</p> <p>Purpose: The polychromatic nature of the x-ray beams and their effects on the reconstructed image are often disregarded during standard image reconstruction. This leads to cupping and beam <span class="hlt">hardening</span> artifacts inside the reconstructed volume. To correct for a general cupping, methods like water precorrection exist. They correct the <span class="hlt">hardening</span> of the spectrum during the penetration of the measured object only for the major tissue class. In contrast, more complex artifacts like streaks between dense objects need other techniques of correction. If using only the information of one single energy scan, there are two types of corrections. The first one is a physical approach. Thereby, artifacts can be reproduced and corrected within the original reconstruction by using assumptions in a polychromatic forward projector. These assumptions could be the used spectrum, the detector response, the physical attenuation and scatter properties of the intersected materials. A second method is an empirical approach, which does not rely on much prior knowledge. This so-called empirical beam <span class="hlt">hardening</span> correction (EBHC) and the previously mentioned physical-based technique are both relying on a segmentation of the present tissues inside the patient. The difficulty thereby is that beam <span class="hlt">hardening</span> by itself, scatter, and other effects, which diminish the image quality also disturb the correct tissue classification and thereby reduce the accuracy of the two known classes of correction techniques. The herein proposed method works similar to the empirical beam <span class="hlt">hardening</span> correction but does not require a tissue segmentation and therefore shows improvements on image data, which are highly degraded by noise and artifacts. Furthermore, the new algorithm is designed in a way that no additional calibration or parameter fitting is needed. Methods: To overcome the segmentation of tissues, the authors propose a histogram deformation of their primary reconstructed CT image. This step is essential for the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22047757','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22047757"><span>ORIGIN OF THE COSMIC-RAY SPECTRAL <span class="hlt">HARDENING</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tomassetti, Nicola</p> <p>2012-06-10</p> <p>Recent data from ATIC, CREAM, and PAMELA indicate that the cosmic-ray energy spectra of protons and nuclei exhibit a remarkable <span class="hlt">hardening</span> at energies above 100 GeV nucleon{sup -1}. We propose that the <span class="hlt">hardening</span> is an interstellar propagation effect that originates from a spatial change of the cosmic-ray transport properties in different regions of the Galaxy. The key hypothesis is that the diffusion coefficient is not separable into energy and space variables as usually assumed. Under this scenario, we can reproduce the observational data well. Our model has several implications for cosmic-ray acceleration/propagation physics and can be tested by ongoing experiments such as the Alpha Magnetic Spectrometer or Fermi-LAT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JMEP...22.1826N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JMEP...22.1826N"><span>Stress and Distortion Evolution During Induction Case <span class="hlt">Hardening</span> of Tube</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nemkov, Valentin; Goldstein, Robert; Jackowski, John; Ferguson, Lynn; Li, Zhichao</p> <p>2013-07-01</p> <p>Simulation of stresses during heat treatment relates usually to furnace heating. Induction heating provides a very different evolution of temperature in the part and therefore different stresses. This may be positive for service properties or negative, reducing component strength or even causing cracks. A method of coupled simulation between electromagnetic, thermal, structural, stress, and deformation phenomena during induction tube <span class="hlt">hardening</span> is described. Commercial software package ELTA is used to calculate the power density distribution in the load resulting from the induction heating process. The program DANTE is used to predict temperature distribution, phase transformations, stress state, and deformation during heating and quenching. Analyses of stress and deformation evolution were made on a simple case of induction <span class="hlt">hardening</span> of external (1st case) and internal (2nd case) surfaces of a thick-walled tubular body.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/138347','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/138347"><span>Recurrence models of <span class="hlt">volcanic</span> events: Applications to <span class="hlt">volcanic</span> risk assessment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Crowe, B.M.; Picard, R.; Valentine, G.; Perry, F.V.</p> <p>1992-03-01</p> <p>An assessment of the risk of future <span class="hlt">volcanism</span> has been conducted for isolation of high-level radioactive waste at the potential Yucca Mountain site in southern Nevada. Risk used in this context refers to a combined assessment of the probability and consequences of future <span class="hlt">volcanic</span> activity. Past studies established bounds on the probability of magmatic disruption of a repository. These bounds were revised as additional data were gathered from site characterization studies. The probability of direct intersection of a potential repository located in an eight km{sup 2} area of Yucca Mountain by ascending basalt magma was bounded by the range of 10{sup {minus}8} to 10{sup {minus}10} yr{sup {minus}1 2}. The consequences of magmatic disruption of a repository were estimated in previous studies to be limited. The exact releases from such an event are dependent on the strike of an intruding basalt dike relative to the repository geometry, the timing of the basaltic event relative to the age of the radioactive waste and the mechanisms of release and dispersal of the waste radionuclides in the accessible environment. The combined low probability of repository disruption and the limited releases associated with this event established the basis for the judgement that the risk of future <span class="hlt">volcanism</span> was relatively low. It was reasoned that that risk of future <span class="hlt">volcanism</span> was not likely to result in disqualification of the potential Yucca Mountain site.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.459...36V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.459...36V"><span>Controls on <span class="hlt">volcanism</span> at intraplate basaltic <span class="hlt">volcanic</span> fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van den Hove, Jackson C.; Van Otterloo, Jozua; Betts, Peter G.; Ailleres, Laurent; Cas, Ray A. F.</p> <p>2017-02-01</p> <p>A broad range of controlling mechanisms is described for intraplate basaltic <span class="hlt">volcanic</span> fields (IBVFs) in the literature. These correspond with those relating to shallow tectonic processes and to deep mantle plumes. Accurate measurement of the physical parameters of intraplate <span class="hlt">volcanism</span> is fundamental to gain an understanding of the controlling factors that influence the scale and location of a specific IBVF. Detailed volume and geochronology data are required for this; however, these are not available for many IBVFs. In this study the primary controls on magma genesis and transportation are established for the Pliocene-Recent Newer <span class="hlt">Volcanics</span> Province (NVP) of south-eastern Australia as a case-study for one of such IBVF. The NVP is a large and spatio-temporally complex IBVF that has been described as either being related to a deep mantle plume, or upper mantle and crustal processes. We use innovative high resolution aeromagnetic and 3D modelling analysis, constrained by well-log data, to calculate its dimensions, volume and long-term eruptive flux. Our estimates suggest <span class="hlt">volcanic</span> deposits cover an area of 23,100 ± 530 km2 and have a preserved dense rock equivalent of erupted <span class="hlt">volcanics</span> of least 680 km3, and may have been as large as 900 km3. The long-term mean eruptive flux of the NVP is estimated between 0.15 and 0.20 km3/ka, which is relatively high compared with other IBVFs. Our comparison with other IBVFs shows eruptive fluxes vary up to two orders of magnitude within individual fields. Most examples where a range of eruptive flux is available for an IBVF show a correlation between eruptive flux and the rate of local tectonic processes, suggesting tectonic control. Limited age dating of the NVP has been used to suggest there were pulses in its eruptive flux, which are not resolvable using current data. These changes in eruptive flux are not directly relatable to the rate of any interpreted tectonic driver such as edge-driven convection. However, the NVP and other</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1003007','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1003007"><span>Sequential circuit design for radiation <span class="hlt">hardened</span> multiple voltage integrated circuits</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Clark, Lawrence T.; McIver, III, John K.</p> <p>2009-11-24</p> <p>The present invention includes a radiation <span class="hlt">hardened</span> sequential circuit, such as a bistable circuit, flip-flop or other suitable design that presents substantial immunity to ionizing radiation while simultaneously maintaining a low operating voltage. In one embodiment, the circuit includes a plurality of logic elements that operate on relatively low voltage, and a master and slave latches each having storage elements that operate on a relatively high voltage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850062457&hterms=maraging+steel&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmaraging%2Bsteel','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850062457&hterms=maraging+steel&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmaraging%2Bsteel"><span>Elastic constant versus temperature behavior of three <span class="hlt">hardened</span> maraging steels</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ledbetter, H. M.; Austin, M. W.</p> <p>1985-01-01</p> <p>Elastic constants of three maraging steels were determined by measuring ultrasonic velocities. Annealed steels show slightly lower bulk moduli and considerably lower shear moduli than <span class="hlt">hardened</span> steels. All the elastic constants (Young's modulus, shear modulus, bulk modulus and Poisson's ratio) show regular temperature behavior between 76 and 400 K. Young's modulus and the shear modulus increase with increasing yield strength, but the bulk modulus and Poisson's ratio are relatively unchanged. Elastic anisotropy is quite small.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA113525','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA113525"><span>Stress Analysis for Kinematic <span class="hlt">Hardening</span> in Finite-Deformation Plasticity.</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1981-12-01</p> <p>field, straight lines defined by material points remain straight and the square block is deformed into a sequence of parallelograms . The line of...Contract N00014-81-K-0660 DEPARTMENT STRESS ANALYSIS FOR KINEMATIC <span class="hlt">HARDENING</span> OF IN FINITE- DEFORMATION PLASTICITY MECHANICAL ENGINEERING By E. H. Lee, R, L...Finite- Deformation Plasticity E. H. Lee and R. L. Mallett, Rensselaer Polytechnic Institute and Stanford University, and T. B. Wertheimer, MARC Analysis</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SPIE.9033E..2VY','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9033E..2VY"><span>Reduction of metal artifacts: beam <span class="hlt">hardening</span> and photon starvation effects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yadava, Girijesh K.; Pal, Debashish; Hsieh, Jiang</p> <p>2014-03-01</p> <p>The presence of metal-artifacts in CT imaging can obscure relevant anatomy and interfere with disease diagnosis. The cause and occurrence of metal-artifacts are primarily due to beam <span class="hlt">hardening</span>, scatter, partial volume and photon starvation; however, the contribution to the artifacts from each of them depends on the type of hardware. A comparison of CT images obtained with different metallic hardware in various applications, along with acquisition and reconstruction parameters, helps understand methods for reducing or overcoming such artifacts. In this work, a metal beam <span class="hlt">hardening</span> correction (BHC) and a projection-completion based metal artifact reduction (MAR) algorithms were developed, and applied on phantom and clinical CT scans with various metallic implants. Stainless-steel and Titanium were used to model and correct for metal beam <span class="hlt">hardening</span> effect. In the MAR algorithm, the corrupted projection samples are replaced by the combination of original projections and in-painted data obtained by forward projecting a prior image. The data included spine fixation screws, hip-implants, dental-filling, and body extremity fixations, covering range of clinically used metal implants. Comparison of BHC and MAR on different metallic implants was used to characterize dominant source of the artifacts, and conceivable methods to overcome those. Results of the study indicate that beam <span class="hlt">hardening</span> could be a dominant source of artifact in many spine and extremity fixations, whereas dental and hip implants could be dominant source of photon starvation. The BHC algorithm could significantly improve image quality in CT scans with metallic screws, whereas MAR algorithm could alleviate artifacts in hip-implants and dentalfillings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6744789','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6744789"><span>Blast response of a <span class="hlt">hardened</span> Army ISO shelter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Milligan, R.W.; Lush, A.; Crenshaw, W.L.</p> <p>1982-09-01</p> <p>A prototype shelter was designed to withstand a blast loading corresponding to a 10.0 psi (68.9 kPa) incident overpressure. The <span class="hlt">hardened</span> shelter was then constructed, instrumented and subjected to a simulated nuclear blast loading. Test results demonstrated that a design featuring shear stiffened sandwich panels with aluminum face materials could withstand a nominal 10.0 psi incident shock loading.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005MSHT...47..434S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005MSHT...47..434S"><span>Structure and Hardness of Cast Iron after Surface <span class="hlt">Hardening</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Safonov, E. N.</p> <p>2005-09-01</p> <p>Special features of structure formation in the heat-affected zone of roll-foundry iron with flaked or globular graphite due to surface heat treatment by direct electric (plasma) arc are considered. The influence of the parameters of the process on the composition, structure, and properties of the <span class="hlt">hardened</span> zone is studied. Treatment modes ensuring a structure with enhanced hardness and wear resistance in the surface layer of iron are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860040780&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHardening','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860040780&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHardening"><span><span class="hlt">Hardening</span> of commercial CMOS PROMs with polysilicon fusible links</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Newman, W. H.; Rauchfuss, J. E.</p> <p>1985-01-01</p> <p>The method by which a commercial 4K CMOS PROM with polysilicon fuses was <span class="hlt">hardened</span> and the feasibility of applying this method to a 16K PROM are presented. A description of the process and the necessary minor modifications to the original layout are given. The PROM circuit and discrete device characteristics over radiation to 1000K rad-Si are summarized. The dose rate sensitivity of the 4K PROMs is also presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/494129','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/494129"><span>Control technology for surface treatment of materials using induction <span class="hlt">hardening</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kelley, J.B.; Skocypec, R.D.</p> <p>1997-04-01</p> <p>In the industrial and automotive industries, induction case <span class="hlt">hardening</span> is widely used to provide enhanced strength, wear resistance, and toughness in components made from medium and high carbon steels. The process uses significantly less energy than competing batch process, is environmentally benign, and is a very flexible in-line manufacturing process. As such, it can directly contribute to improved component reliability, and the manufacture of high-performance lightweight parts. However, induction <span class="hlt">hardening</span> is not as widely used as it could be. Input material and unexplained process variations produce significant variation in product case depth and quality. This necessitates frequent inspection of product quality by destructive examination, creates higher than desired scrap rates, and causes de-rating of load stress sensitive components. In addition, process and tooling development are experience-based activities, accomplished by trial and error. This inhibits the use of induction <span class="hlt">hardening</span> for new applications, and the resultant increase in energy efficiency in the industrial sectors. In FY96, a Cooperative Research and Development Agreement under the auspices of the Technology Transfer Initiative and the Partnership for a New Generation of Vehicles was completed. A multidisciplinary team from Sandia National Labs and Delphi Saginaw Steering Systems investigated the induction <span class="hlt">hardening</span> by conducting research in the areas of process characterization, computational modeling, materials characterization, and high speed data acquisition and controller development. The goal was to demonstrate the feasibility of closed-loop control for a specific material, geometry, and process. Delphi Steering estimated annual savings of $2-3 million per year due to reduced scrap losses, inspection costs, and machine down time if reliable closed-loop control could be achieved. A factor of five improvement in process precision was demonstrated and is now operational on the factory floor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA181905','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA181905"><span>Variations in the Bainite <span class="hlt">Hardenability</span> of ASTM A723 Steel</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1987-05-01</p> <p>REFERENCES 10 TABLES I. CHEMICAL ANALYSIS OF SAMPLES FROM ESR , CONVENTIONALLY REFINED, 5 AND CALCIUM TREATED STEELS II. COMPARISON OF LABORATORY...balnite formation is detected in the ESR refined sample. However, our survey of A723 steels from a number of suppliers who employ various refining tech...<span class="hlt">hardenability</span> steels that we have analyzed have nickel concentrations near two percent. The ESR sample is typical of alloys that we classify as high</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5626568','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5626568"><span>Work-<span class="hlt">hardening</span> and effective viscosity in solid beryllium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Steinberg, D.; Breithaupt, D.; Honodel, C.</p> <p>1985-06-01</p> <p>Results from Hopkinson split-bar, plate-impact, and cylinder deceleration experiments on beryllium are compared with hydrodynamic computer code simulations. By substantially increasing the beryllium work-<span class="hlt">hardening</span> in the Steinberg-Guinan constitutive model, excellent agreement between the experiments and the calculations is achieved. A model to estimate effective viscosity is also proposed and the resultant calculations are in reasonable agreement with those derived from another model advanced by Asay, Chhabildas and Wise. 12 refs., 5 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28269812','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28269812"><span>Multi-material linearization beam <span class="hlt">hardening</span> correction for computed tomography.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lifton, J J</p> <p>2017-03-03</p> <p>Since beam <span class="hlt">hardening</span> causes cupping and streaking artifacts in computed tomographic images, the presence of such artifacts can impair both qualitative and quantitative analysis of the reconstructed data. When the scanned object is composed of a single material, it is possible to correct beam <span class="hlt">hardening</span> artifacts using the linearization method. However, for multi-material objects, an iterative segmentation-based correction algorithm is needed, which is not only computationally expensive, but may also fail if the initial segmentation result is poor. In this study, a new multi-material linearization beam <span class="hlt">hardening</span> correction method was proposed and evaluated. The new method is fast and implemented in the same manner as a mono-material linearization. The correction takes approximately 0.02 seconds per projection. Although facing a potential disadvantage of requiring attenuation measurements of one of the object's constituent materials, applying the new method has demonstrated its capability for a multi-material workpiece with substantial reduction in both cupping and streaking artifacts. For example, the study showed that the absolute cupping artefacts in steel, titanium and aluminum spheres were reduced from 22%, 20% and 20% to 5%, 1% and 0%, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27563511','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27563511"><span>Description of full-range strain <span class="hlt">hardening</span> behavior of steels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Tao; Zheng, Jinyang; Chen, Zhiwei</p> <p>2016-01-01</p> <p>Mathematical expression describing plastic behavior of steels allows the execution of parametric studies for many purposes. Various formulas have been developed to characterize stress strain curves of steels. However, most of those formulas failed to describe accurately the strain <span class="hlt">hardening</span> behavior of steels in the full range which shows various distinct stages. For this purpose, a new formula is developed based on the well-known Ramberg-Osgood formula to describe the full range strain <span class="hlt">hardening</span> behavior of steels. Test results of all the six types of steels show a three-stage strain <span class="hlt">hardening</span> behavior. The proposed formula can describe such behavior accurately in the full range using a single expression. The parameters of the formula can be obtained directly and easily through linear regression analysis. Excellent agreements with the test data are observed for all the steels tested. Furthermore, other formulas such as Ludwigson formula, Gardner formula, UGent formula are also applied for comparison. Finally, the proposed formula is considered to have wide suitability and high accuracy for all the steels tested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JMEP...22.3258I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JMEP...22.3258I"><span>Simulation of Stress and Strain for Induction-<span class="hlt">Hardening</span> Applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ivanov, Dmitry; Markegård, Leif; Asperheim, John Inge; Kristoffersen, Hans</p> <p>2013-11-01</p> <p>The possibility to manage stress and strain in <span class="hlt">hardened</span> parts might be beneficial for a number of induction-<span class="hlt">hardening</span> applications. The most important of these benefits are the improvement of fatigue strength, avoidance of cracks, and minimization of distortion. An appropriate and powerful way to take the stress and strain into account during the development of a process is to make use of computer simulations. In-house developed and commercial software packages have been coupled to incorporate the electromagnetic task into the calculations. The simulations have been performed followed by analysis of the results. The influences of two different values of quenching intensity, strength of initial material structure, strength of austenite, surface power density-frequency-time combination, and workpiece diameter on the residual stress are studied. The influence of quenching intensity is confirmed by the series of experiments representing the external <span class="hlt">hardening</span> of a cylinder with eight variations of quenching intensity. Measured by x-rays, the values of surface tangential stress are used as a dataset for verification of the model being used for analyses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010HyInt.195...35A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010HyInt.195...35A"><span>Magnetic minerals from <span class="hlt">volcanic</span> Ultisols as heterogeneous Fenton catalysts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aravena, S.; Pizarro, C.; Rubio, M. A.; Cavalcante, L. C. D.; Garg, V. K.; Pereira, M. C.; Fabris, J. D.</p> <p>2010-01-01</p> <p>This study was devoted to the evaluation of the effectiveness of Fenton catalysts, based on magnetically-concentrated portions of iron oxide-rich sand fractions from two magnetic Ultisols, derived from <span class="hlt">volcanic</span> materials of southern Chile. The samples were labeled according to the municipality where the sample sites are geographically located, namely Metrenco and Collipulli, and were characterized with Mössbauer spectroscopy at 298 K and saturation magnetization ( σ) measurements. Mössbauer data revealed a complex magnetic hyperfine structure for these magnetic portions from both <span class="hlt">soil</span>-sand materials, suggesting relatively complex mineral assemblages. The monitored rate of H2O2 decomposition via heterogeneous Fenton reaction revealed that materials from the Collipulli <span class="hlt">soil</span> are more efficient Fenton catalyst than are those from the Metrenco <span class="hlt">soil</span>. The reasons for these differences are from now on being explored on basis of a more detailed chemical investigation of these samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/138320','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/138320"><span>Geochemical evidence for waning magmatism and polycyclic <span class="hlt">volcanism</span> at Crater Flat, Nevada</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Perry, F.V.; Crowe, B.M.</p> <p>1991-12-31</p> <p>Petrologic and geochemical studies of basaltic rocks in the Yucca Mountain region are currently focused on understanding the evolution of <span class="hlt">volcanism</span> in the Crater Flat <span class="hlt">volcanic</span> field and the mechanisms of polycyclic <span class="hlt">volcanism</span> at the Lathrop Wells <span class="hlt">volcanic</span> center, the youngest center in the Crater Flat <span class="hlt">volcanic</span> field. Geochemical and petrologic data indicate that the magma chambers which supplied the <span class="hlt">volcanic</span> centers in Crater Flat became situated at greater crustal depths as the field evolved. Deep magma chambers may be related to a waning magma flux that was unable to sustain upper crystal magma conduits and chambers. Geochemical data from the Lathrop Wells <span class="hlt">volcanic</span> center indicate that eruptive units identified from field and geomorphic relationships are geochemically distinct. The geochemical variations cannot be explained by fractional crystallization of a single magma batch, indicating that several magma batches were involved in the formation of the Lathrop Wells center. Considering the low magma flux in the Yucca Mountain region in the Quaternary, the probability of several magma batches erupting essentially simultaneously at Lathrop Wells in considered remote. It is more likely that the Lathrop Wells center was formed by a series of eruptions that took place over many thousands of years. The geochemical data from Lathrop Wells is consistent with the concept of a complex, polycyclic volcano, which was originally proposed based on geomorphic and <span class="hlt">soil</span>-development data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V44B..06P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V44B..06P"><span>Diffuse Helium Emission as a Precursory Sign of <span class="hlt">Volcanic</span> Unrest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Padron, E.; Perez, N.; Hernandez Perez, P. A.; Sumino, H.; Melian Rodriguez, G.; Barrancos, J.; Nolasco, D.; Padilla, G.; Dionis, S.; Rodriguez, F.; Hernandez, I.; Calvo, D.; Peraza, M.; Nagao, K.</p> <p>2012-12-01</p> <p>Since July 16, 2011, an anomalous seismicity at El Hierro island, the youngest and smallest of the Canary Islands, was recorded by IGN seismic network. After the occurrence of more than 10,000 seismic events, <span class="hlt">volcanic</span> tremor was recorded since 05:15 of the October 10, by all of the seismic stations on the island, with highest amplitudes recorded in the southernmost station. During the afternoon of October 12 a large light-green coloured area was observed in the sea to the souht of La Restinga village (at the southernmost part of El Hierro island), suggesting the existence of a submarine eruption. Since October 12, frequent episodes of, turbulent gas emission and foaming, and the appearance of steamy lava fragments has been observed on the sea surface. As part of the <span class="hlt">volcanic</span> surveillance of the island, the Instituto Volcanologico de Canarias (INVOLCAN) geochemical monitoring program is carrying out diffuse helium surveys on the surface environment of El Hierro (<span class="hlt">soil</span> atmosphere). This nobel gas has been investigated because it has been considered an almost ideal geochemical indicator because it is chemically inert, physically stable, nonbiogenic, sparingly soluble in water under ambient conditions and almost non-adsorbable. At each survey, 600 sampling sites covering the whole island and following an homogeneous distribution are selected for helium measurements in the <span class="hlt">soil</span> gases, The helium concentration gradients with respect to its value on air (5.24 ppm) allow us to estimate a pure diffusive emission rate of helium throughout the island. The first survey was carried out on the summer of 2003, when the island was on a quiescence period. At this survey, the amount of helium released by the <span class="hlt">volcanic</span> system of El Hierro was estimated in 6 kg/d. Since the beginning of the seismic unrest, 13 helium emission surveys have been carried out. The helium emission rate has shown an excellent agreement with the evolution of the <span class="hlt">volcanic</span> crisis of the island, reaching 30 kg</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720040000&hterms=Bellcomm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DBellcomm','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720040000&hterms=Bellcomm&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DBellcomm"><span>Descartes region - Evidence for Copernican-age <span class="hlt">volcanism</span>.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Head, J. W., III; Goetz, A. F. H.</p> <p>1972-01-01</p> <p>A model that suggests that the high-albedo central region of the Descartes Formation was formed by Copernican-age <span class="hlt">volcanism</span> was developed from Orbiter photography, Apollo 12 multispectral photography, earth-based spectrophotometry, and thermal IR and radar data. The bright surface either is abundant in centimeter-sized rocks or is formed from an insulating debris layer overlying a surface with an abundance of rocks in the 1- to 20-cm size range. On the basis of these data, the bright unit is thought to be a young pyroclastic deposit mantling older <span class="hlt">volcanic</span> units of the Descartes Formation. Since the Apollo 16 target point is only 50 km NW of the central part of this unit, evidence for material associated with this unique highland formation should be searched for in returned <span class="hlt">soil</span> and rock samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760062879&hterms=Pumice&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPumice','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760062879&hterms=Pumice&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPumice"><span><span class="hlt">Volcanic</span> ash - Terrestrial versus extraterrestrial</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Okeefe, J. A.</p> <p>1976-01-01</p> <p>A principal difference between terrestrial and extraterrestrial lavas may consist in the greater ability of terrestrial lavas to form thin films (like those of soap bubbles) and hence foams. It would follow that, in place of the pumice and spiny shards found in terrestrial <span class="hlt">volcanic</span> ash, an extraterrestrial ash should contain minute spherules. This hypothesis may help to explain lunar microspherules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21443190','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21443190"><span>DETECTING <span class="hlt">VOLCANISM</span> ON EXTRASOLAR PLANETS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kaltenegger, L.; Sasselov, D. D.; Henning, W. G.</p> <p>2010-11-15</p> <p>The search for extrasolar rocky planets has already found the first transiting rocky super-Earth, Corot 7b, with a surface temperature that allows for magma oceans. Here, we investigate whether we could distinguish rocky planets with recent major <span class="hlt">volcanism</span> by remote observation. We develop a model for <span class="hlt">volcanic</span> eruptions on an Earth-like exoplanet based on the present-day Earth and derive the observable features in emergent and transmission spectra for multiple scenarios of gas distribution and cloud cover. We calculate the observation time needed to detect explosive <span class="hlt">volcanism</span> on exoplanets in primary as well as secondary eclipse and discuss the likelihood of observing <span class="hlt">volcanism</span> on transiting Earth-sized to super-Earth-sized exoplanets. We find that sulfur dioxide from large explosive eruptions does present a spectral signal that is remotely detectable especially for secondary eclipse measurements around the closest stars and ground-based telescopes, and report the frequency and magnitude of the expected signatures. The transit probability of a planet in the habitable zone decreases with distance from the host star, making small, nearby host stars the best targets.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813473M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813473M"><span>Infrasound research of <span class="hlt">volcanic</span> eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchetti, Emanuele; Ripepe, Maurizio</p> <p>2016-04-01</p> <p><span class="hlt">Volcanic</span> eruptions are efficient sources of infrasound produced by the rapid perturbation of the atmosphere by the explosive source. Being able to propagate up to large distances from the source, infrasonic waves from major (VEI 4 or larger) <span class="hlt">volcanic</span> eruptions have been recorded for many decades with analogue micro-barometers at large regional distances. In late 1980s, near-field observations became progressively more common and started to have direct impact on the understanding and modeling of explosive source dynamics, to eventually play a primary role in volcano research. Nowadays, infrasound observation from a large variety of <span class="hlt">volcanic</span> eruptions, spanning from VEI 0 to VEI 5 events, has shown a dramatic variability in terms of signature, excess pressure and frequency content of radiated infrasound and has been used to infer complex eruptive source mechanisms for the different kinds of events. Improved processing capability and sensors has allowed unprecedented precise locations of the explosive source and is progressively increasing the possibility to monitor volcanoes from distant records. Very broadband infrasound observations is also showing the relation between <span class="hlt">volcanic</span> eruptions and the atmosphere, with the eruptive mass injection in the atmosphere triggering acoustic-gravity waves which eventually might control the ash dispersal and fallout.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPSC...10..915P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPSC...10..915P"><span>Putative <span class="hlt">volcanic</span> landforms on Ceres</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Platz, T.; Nathues, A.; Hoffmann, M.; Schäfer, M.; Williams, D. A.; Mest, S. C.; Crown, D. A.; Sykes, M. V.; Li, J.-Y.; Kneissl, T.; Schmedemann, N.; Ruesch, O.; Hiesinger, H.; Sizemore, H.; Büttner, I.; Gutierrez-Marques, P.; Ripken, J.; Raymond, C. A.; Russell, C. T.; Schäfer, T.</p> <p>2015-10-01</p> <p>In the first RC2 and OpNav7 images of Dawn's approach at Ceres a number of intriguing landforms are observed, which potentially have formed by <span class="hlt">volcanic</span> activity. These and subsequently discovered features will be monitored and validated on higher resolution datasets as acquired later in 2015.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.9004C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.9004C"><span>Experimental generation of <span class="hlt">volcanic</span> lightning</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cimarelli, Corrado; Alatorre-Ibargüengoitia, Miguel; Kueppers, Ulrich; Scheu, Bettina; Dingwell, Donald B.</p> <p>2014-05-01</p> <p>Ash-rich <span class="hlt">volcanic</span> plumes that are responsible for injecting large quantities of aerosols into the atmosphere are often associated with intense electrical activity. Direct measurement of the electric potential at the crater, where the electric activity in the <span class="hlt">volcanic</span> plume is first observed, is severely impeded, limiting progress in its investigation. We have achieved <span class="hlt">volcanic</span> lightning in the laboratory during rapid decompression experiments of gas-particle mixtures under controlled conditions. Upon decompression (from ~100 bar argon pressure to atmospheric pressure), loose particles are vertically accelerated and ejected through a nozzle of 2.8 cm diameter into a large tank filled with air at atmospheric conditions. Because of their impulsive character, our experiments most closely represent the conditions encountered in the gas-thrust region of the plume, when ash is first ejected from the crater. We used sieved natural ash with different grain sizes from Popocatépetl (Mexico), Eyjafjallajökull (Iceland), and Soufrière Hills (Montserrat) volcanoes, as well as micrometric glass beads to constrain the influence of material properties on lightning. We monitored the dynamics of the particle-laden jets with a high-speed camera and the pressure and electric potential at the nozzle using a pressure transducer and two copper ring antennas connected to a high-impedance data acquisition system, respectively. We find that lightning is controlled by the dynamics of the particle-laden jet and by the abundance of fine particles. Two main conditions are required to generate lightning: 1) self-electrification of the particles and 2) clustering of the particles driven by the jet fluid dynamics. The relative movement of clusters of charged particles within the plume generates the gradient in electrical potential, which is necessary for lightning. In this manner it is the gas-particle dynamics together with the evolving particle-density distribution within different regions of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013aero.confE.330V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013aero.confE.330V"><span>Performance of radiation <span class="hlt">hardening</span> techniques under voltage and temperature variations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Veeravalli, Varadan Savulimedu; Steininger, Andreas</p> <p></p> <p>The effectiveness of the techniques to mitigate radiation particle hits in digital CMOS circuits has been mainly studied under a given set of environmental conditions. This paper will explicitly analyze, how the performance of two selected radiation <span class="hlt">hardening</span> techniques, namely transistor sizing and stack separation, varies with temperature and supply voltage. Our target is an inverter circuit in UMC90 bulk CMOS technology, instances of which have been <span class="hlt">hardened</span> against charges of 300fC and 450fC using either of the two techniques under investigation. In a Spice simulation we apply particle hits to these circuits through double-exponential current pulses of the respective charge. We study the effect of these pulses in a temperature range from - 55 C to +175 C and a supply voltage of 0.65 to 1.2V (nominal 1V) at the output of a (unhardened) buffer that has been connected as a load. For the <span class="hlt">hardening</span> by sizing we observe proper operation in the range from 1.2V to 900mV, while for lower supply we observe full swing pulses of increasing magnitude when the respective maximum charge is applied. The influence of temperature turns out to be minor. For the stack separation approach the observation is similar, however, the circuit starts glitching only at 750mV. Our study allows the following conclusions: (i) The effectiveness of the <span class="hlt">hardening</span> approaches strongly depends on the supply voltage, and moderately on temperature. (ii) As expected, low voltage and high temperature represent the worst case for rad-hard sizing. Stack separation, on the other hand, unexpectedly shows a stronger and more complicated temperature dependence. (ii) For voltages below approx. 90% of nominal the <span class="hlt">hardening</span> by sizing fails, when designed for nominal voltage and room temperature. The approach can be enhanced to survive this worst case by increasing the sizing factor further by more than 3 times. (iv) The stack separation only fails for voltages below approx. 75% of nominal, but there is n</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5579483','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5579483"><span><span class="hlt">Volcanic</span> Aerosol Phosphorus, Chlorine, and Sulfur at Kilauea, Hawaii</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Darzi, M.; Winchester, J.W.</p> <p>1982-12-20</p> <p>Aerosol concentrations of P, Cl, S, and major <span class="hlt">soil</span>-derived elements were measured sequentially at the Hawaiian Volcano Observatory (HVO) from March to September 1979, with 3.7-hour time resolution using a Nucleopore-filter sampler. The filters were analyzed by particle-induced X ray emission (PIXE). Comparison with diurnal variations in the air flow inferred from major <span class="hlt">soil</span> elements, e.g., Fe, as well as measurements made previously at fumaroles near HVO, indicate that the P, C. and S may be attributed mainly to <span class="hlt">volcanic</span> emissions from Kilauea. From April 23 to June 30, P was found with concentrations up to 1000 ng m/sup -3/; but before and after those dates, P was generally below the detection limit of 50--80 ng m/sup -3/. Cl and S were frequently found over the entire sampling period, also with concentrations up to 1000 ng m/sup -3/. However, when P was found, Cl was almost never detected simultaneously. The mutually exclusive occurrences of P and Cl suggest volatility release of HCl from aerosol particles by reaction with strong acid associated with P. If strong acidity is due to H/sub 2/SO/sub 4/, it is not well predicted by S, which may also include other sulfates or sulfur, since aerosol S concentrations are not well correlated with P or Cl. The behavior of these three elements suggests that the <span class="hlt">volcanic</span> sources of P are more localized than those of Cl or S. It is significant that concentrations of aerosol P can be as high as aerosol Cl and S, all apparently of primary <span class="hlt">volcanic</span> origin, indicating that <span class="hlt">volcanism</span> may be an important, but hitherto unrecognized, process in the atmosphere goechemical cycling of phosphorus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26498821','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26498821"><span>An improved effective microorganism (EM) <span class="hlt">soil</span> ball-making method for water quality restoration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Gun-Seok; Khan, Abdur Rahim; Kwak, Yunyoung; Hong, Sung-Jun; Jung, ByungKwon; Ullah, Ihsan; Kim, Jong-Guk; Shin, Jae-Ho</p> <p>2016-01-01</p> <p><span class="hlt">Soil</span> balls containing the so-called effective microorganisms (EM) have been applied to improve water quality of small ponds, lakes, and streams worldwide. However, neither the physical conditions facilitating their proper application nor the diversity of microbial community in such <span class="hlt">soil</span> balls have been investigated. In this study, the application of 0.75% of <span class="hlt">hardener</span> to the <span class="hlt">soil</span> balls exerted almost neutral pH (pH 7.3) which caused up to a fourfold increased hardness of the <span class="hlt">soil</span> ball. Moreover, the 0.75% of <span class="hlt">hardener</span> in the <span class="hlt">soil</span> ball also improved the water quality due to a significant reduction in dissolved oxygen, total phosphorus, and total nitrogen contents. Metagenomic analysis of the microbial community in the <span class="hlt">soil</span> ball with 0.75% <span class="hlt">hardener</span> was compared with control (traditional <span class="hlt">soil</span> ball) through next-generation sequencing. The traditional <span class="hlt">soil</span> ball microbial community comprised 96.1% bacteria, 2.7% eukaryota, and 1% archaea, whereas the <span class="hlt">soil</span> ball with 0.75% <span class="hlt">hardener</span> comprised 71.4% bacteria, 27.9% eukaryota, and 0.2% viruses. Additionally, metagenomic profiles for both traditional and improved <span class="hlt">soil</span> balls revealed that the various xenobiotic biodegradation, such as those for caprolactam, atrazine, xylene, toluene, styrene, bisphenol, and chlorocyclohexane might be responsible for organic waste cleanup.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...837L...4R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...837L...4R"><span>A <span class="hlt">Volcanic</span> Hydrogen Habitable Zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramirez, Ramses M.; Kaltenegger, Lisa</p> <p>2017-03-01</p> <p>The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N2–CO2–H2O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO2 outstrips its greenhouse capacity. Here, we show that <span class="hlt">volcanic</span> outgassing of atmospheric H2 can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider <span class="hlt">volcanic</span>-hydrogen HZ (N2–CO2–H2O–H2) can be sustained as long as <span class="hlt">volcanic</span> H2 output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this <span class="hlt">volcanic</span> hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H2 warming is reduced in dense H2O atmospheres. The atmospheric scale heights of such <span class="hlt">volcanic</span> H2 atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6094501','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6094501"><span>Influence of Mount St. Helens <span class="hlt">volcanic</span> ash on alfalfa growth and nutrient uptake</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mahler, R.L.</p> <p>1984-01-01</p> <p>Concern has been expressed that large amounts of <span class="hlt">volcanic</span> ash from the May 18, 1980 eruption of Mount St. Helens may have created potential nutritional problems associated with forage production in northern Idaho and eastern Washington to the extent that adjustments need to be made in <span class="hlt">soil</span> test correlation data. The objectives of this greenhouse study were to : (1) determine the effect of varying amounts of <span class="hlt">volcanic</span> ash mixed into <span class="hlt">soils</span> of northern Idaho on total alfalfa biomass production, and (2) to determine the effect of various <span class="hlt">soil</span>/ash mixtures on the nutrient concentrations of P, K, S, Ca, Mg, Mn and Zn in alfalfa. Alfalfa was grown in eight different northern Idaho <span class="hlt">soils</span> amended with differing levels of <span class="hlt">volcanic</span> ash (0, 20, 35, 50 and 75%) in the greenhouse. The alfalfa seeds were inoculated and fertilizer P and S were added to all treatments. Total plant biomass and P, K, S, Ca, Mg, Mn and Zn plant concentrations were measured. The eight were pooled for analysis and it was found that increasing amounts of <span class="hlt">volcanic</span> ash increased alfalfa biomass production. Plant P, S, Ca, Mg and Zn concentrations also increased with increasing levels of ash. Conversely, increasing levels of ash resulted in lower alfalfa tissue K and Mn concentrations. 13 references, 7 figures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V13D2633W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V13D2633W"><span>How <span class="hlt">Volcanism</span> Controls Climate Change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ward, P. L.</p> <p>2013-12-01</p> <p>Large explosive volcanoes eject megatons of sulfur dioxide into the lower stratosphere where it spreads around the world within months and is oxidized slowly to form a sulfuric-acid aerosol with particle sizes that grow large enough to reflect and scatter solar radiation, cooling Earth ~0.5C for up to 3 years. Explosive eruptions also deplete total column ozone ~6% causing up to 3C winter warming at mid-latitudes over continents. Global cooling predominates. Extrusive, basaltic volcanoes deplete ozone ~6% but do not eject much sulfur dioxide into the lower stratosphere, causing net global warming. Anthropogenic chlorofluorocarbons (CFCs) deplete ozone ~3% for up to a century while each <span class="hlt">volcanic</span> eruption, even small ones, depletes ozone twice as much but for less than a decade through eruption of halogens and ensuing photochemical processes. The 2010 eruption of Eyjafjallajökull, the 2011 eruption of Grímsvötn, plus anthropogenic CFCs depleted ozone over Toronto Canada 14% in 2012, causing an unusually warm winter and drought. Total column ozone determines how much solar ultraviolet energy with wavelengths between 290 and 340 nanometers reaches Earth where it is absorbed most efficiently by the ocean. A 25% depletion of ozone increases the amount of this radiation reaching Earth by 1 W m-2 for overhead sun and 0.25 W m-2 for a solar zenith angle of 70 degrees. The tropopause is the boundary between the troposphere heated from below by a sun-warmed Earth and the stratosphere heated from above by the Sun through photodissociation primarily of oxygen and ozone. The mean annual height of the tropopause increased ~160 m between 1980 and 2004 at the same time that northern mid-latitude total column ozone was depleted by ~4%, the lower stratosphere cooled ~2C, the upper troposphere warmed ~0.1C, and mean surface temperatures in the northern hemisphere rose ~0.5C. Regional total ozone columns are observed to increase as rapidly as 20% within 5 hours with an associated 5</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6063457','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6063457"><span>Initial development of the Banda <span class="hlt">Volcanic</span> Arc</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hartono, H.M.S. )</p> <p>1990-06-01</p> <p>The initial development of the Banda <span class="hlt">Volcanic</span> Arc can be determined by obtaining absolute ages of granites or <span class="hlt">volcanics</span>, stratigraphy of the Eocene Metan <span class="hlt">Volcanics</span> of Timor as the oldest formation containing Banda <span class="hlt">Volcanic</span> Arc extrusives, and tectonic analysis. Banda Arc <span class="hlt">volcanism</span> is the result of subduction of oceanic crust under the <span class="hlt">volcanic</span> arc. The time of initial subduction is related to initial seafloor spreading between Australia and Antarctica, which is identical to geomagnetic polarity time 34 (82 mybp). Therefore, 82 mybp can be used as one of the criteria to determine the birth of the Banda <span class="hlt">Volcanic</span> Arc. With present available time data for determining the birth of the Banda <span class="hlt">Volcanic</span> Arc, the minimum age coincides with the age of the Metan <span class="hlt">Volcanics</span> (Eocene, 39-56 mybp) and the maximum age coincides with initial seafloor spreading between Australia and Antarctica (82 mybp). This time span is too long. With the assumption that it needs some time to develop from transcurrent faulting to subduction and <span class="hlt">volcanism</span>, it is proposed that the initial development of Banda Arc <span class="hlt">volcanism</span> was during early Tertiary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980deav.rept.....C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980deav.rept.....C"><span>Disruptive event analysis: <span class="hlt">Volcanism</span> and igneous intrusion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crowe, B. M.</p> <p>1980-08-01</p> <p>An evaluation was made of the disruptive effects of <span class="hlt">volcanic</span> activity with respect to long term isolation of radioactive waste through deep geologic storage. Three major questions were considered. First, what is the range of disruption effects of a radioactive waste repository by <span class="hlt">volcanic</span> activity. Second, is it possible, by selective siting of a repository to reduce the risk of disruption by future <span class="hlt">volcanic</span> activity. And third, can the probability of repository disruption by <span class="hlt">volcanic</span> activity be quantified. The main variables involved in the evaluation of the consequences of repository disruption by <span class="hlt">volcanic</span> activity were the geometry of the magma repository intersection (partly controlled by depth of burial) and the nature of <span class="hlt">volcanism</span>. Simplified probability calculations were attempted for areas of past <span class="hlt">volcanic</span> activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/871207','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/871207"><span>Method for increasing the rate of compressive strength gain in <span class="hlt">hardenable</span> mixtures containing fly ash</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.</p> <p>1997-01-01</p> <p>The present invention relates to concrete, mortar and other <span class="hlt">hardenable</span> mixtures comprising cement and fly ash for use in construction. The invention provides a method for increasing the rate of strength gain of a <span class="hlt">hardenable</span> mixture containing fly ash by exposing the fly ash to an aqueous slurry of calcium oxide (lime) prior to its incorporation into the <span class="hlt">hardenable</span> mixture. The invention further relates to such <span class="hlt">hardenable</span> mixtures, e.g., concrete and mortar, that contain fly ash pre-reacted with calcium oxide. In particular, the fly ash is added to a slurry of calcium oxide in water, prior to incorporating the fly ash in a <span class="hlt">hardenable</span> mixture. The <span class="hlt">hardenable</span> mixture may be concrete or mortar. In a specific embodiment, mortar containing fly ash treated by exposure to an aqueous lime slurry are prepared and tested for compressive strength at early time points.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/541716','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/541716"><span>Method for increasing the rate of compressive strength gain in <span class="hlt">hardenable</span> mixtures containing fly ash</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.</p> <p>1997-10-28</p> <p>The present invention relates to concrete, mortar and other <span class="hlt">hardenable</span> mixtures comprising cement and fly ash for use in construction. The invention provides a method for increasing the rate of strength gain of a <span class="hlt">hardenable</span> mixture containing fly ash by exposing the fly ash to an aqueous slurry of calcium oxide (lime) prior to its incorporation into the <span class="hlt">hardenable</span> mixture. The invention further relates to such <span class="hlt">hardenable</span> mixtures, e.g., concrete and mortar, that contain fly ash pre-reacted with calcium oxide. In particular, the fly ash is added to a slurry of calcium oxide in water, prior to incorporating the fly ash in a <span class="hlt">hardenable</span> mixture. The <span class="hlt">hardenable</span> mixture may be concrete or mortar. In a specific embodiment, mortar containing fly ash treated by exposure to an aqueous lime slurry are prepared and tested for compressive strength at early time points. 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/138145','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/138145"><span>Preliminary geologic map of the Sleeping Butte <span class="hlt">volcanic</span> centers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Crowe, B.M.; Perry, F.V.</p> <p>1991-07-01</p> <p>The Sleeping Butte <span class="hlt">volcanic</span> centers comprise two, spatially separate, small-volume (<0.1 km{sup 3}) basaltic centers. The centers were formed by mildly explosive Strombolian eruptions. The Little Black Peak cone consists of a main scoria cone, two small satellitic scoria mounds, and associated lobate lava flows that vented from sites at the base of the scoria cone. The Hidden Cone center consists of a main scoria cone that developed on the north-facing slope of Sleeping Butte. The center formed during two episodes. The first included the formation of the main scoria cone, and venting of aa lava flows from radial dikes at the northeast base of the cone. The second included eruption of scoria-fall deposits from the summit crater. The ages of the Little Black Peak and the Hidden Cone are estimated to be between 200 to 400 ka based on the whole-rock K-Ar age determinations with large analytical undertainty. This age assignment is consistent with qualitative observations of the degree of <span class="hlt">soil</span> development and geomorphic degradation of <span class="hlt">volcanic</span> landforms. The younger episode of the Hidden Cone is inferred to be significantly younger and probably of Late Pleistocene or Holocene age. This is based on the absence of cone slope rilling, the absence of cone-slope apron deposits, and erosional unconformity between the two episodes, the poor horizon- development of <span class="hlt">soils</span>, and the presence of fall deposits on modern alluvial surfaces. Paleomagnetic data show that the centers record similar but not identical directions of remanent magnetization. Paleomagnetic data have not been obtained for the youngest deposits of the Hidden Cone center. Further geochronology, <span class="hlt">soils</span>, geomorphic, and petrology studies are planned of the Sleeping Butte <span class="hlt">volcanic</span> centers 20 refs., 3 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22531203','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22531203"><span>Multi-MGy Radiation <span class="hlt">Hardened</span> Camera for Nuclear Facilities</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Girard, Sylvain; Boukenter, Aziz; Ouerdane, Youcef; Goiffon, Vincent; Corbiere, Franck; Rolando, Sebastien; Molina, Romain; Estribeau, Magali; Avon, Barbara; Magnan, Pierre; Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Raine, Melanie</p> <p>2015-07-01</p> <p>There is an increasing interest in developing cameras for surveillance systems to monitor nuclear facilities or nuclear waste storages. Particularly, for today's and the next generation of nuclear facilities increasing safety requirements consecutive to Fukushima Daiichi's disaster have to be considered. For some applications, radiation tolerance needs to overcome doses in the MGy(SiO{sub 2}) range whereas the most tolerant commercial or prototypes products based on solid state image sensors withstand doses up to few kGy. The objective of this work is to present the radiation <span class="hlt">hardening</span> strategy developed by our research groups to enhance the tolerance to ionizing radiations of the various subparts of these imaging systems by working simultaneously at the component and system design levels. Developing radiation-<span class="hlt">hardened</span> camera implies to combine several radiation-<span class="hlt">hardening</span> strategies. In our case, we decided not to use the simplest one, the shielding approach. This approach is efficient but limits the camera miniaturization and is not compatible with its future integration in remote-handling or robotic systems. Then, the <span class="hlt">hardening</span>-by-component strategy appears mandatory to avoid the failure of one of the camera subparts at doses lower than the MGy. Concerning the image sensor itself, the used technology is a CMOS Image Sensor (CIS) designed by ISAE team with custom pixel designs used to mitigate the total ionizing dose (TID) effects that occur well below the MGy range in classical image sensors (e.g. Charge Coupled Devices (CCD), Charge Injection Devices (CID) and classical Active Pixel Sensors (APS)), such as the complete loss of functionality, the dark current increase and the gain drop. We'll present at the conference a comparative study between these radiation-<span class="hlt">hardened</span> pixel radiation responses with respect to conventional ones, demonstrating the efficiency of the choices made. The targeted strategy to develop the complete radiation hard camera electronics will</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18959197','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18959197"><span>[The effect of daily exposure to low <span class="hlt">hardening</span> temperature on plant vital activity].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Markovskaia, E F; Sysoeva, M I; Sherudilo, E G</p> <p>2008-01-01</p> <p>Phenomenological responses of plants to daily short-term exposure to low <span class="hlt">hardening</span> temperature was studied under chamber and field conditions. Experiments were carried out on cucumber (Cucumis sativus L.), barley (Hordeum vulgare L.), marigolds (Tagetes L.), and petunia (Petunia x hybrida) plants. The obtained data demonstrated a similar pattern of response in all studied plant species to different variants of exposure to low <span class="hlt">hardening</span> temperature. The main features of plant response to daily short-term exposure to low <span class="hlt">hardening</span> temperature include: a higher rate of increase in cold tolerance (cf. two- or threefold increase relative to constant low <span class="hlt">hardening</span> temperature) that peaked on day 5 (cf. day 2 at constant low <span class="hlt">hardening</span> temperature) and was maintained for 2 weeks (cf. 3-4 days at constant low <span class="hlt">hardening</span> temperature); a simultaneous increase in heat tolerance (cf. twofold relative to constant low <span class="hlt">hardening</span> temperature) maintained over a long period (cf. only in the beginning of the exposure to constant low <span class="hlt">hardening</span> temperature); a sharp drop in the subsequent cold tolerance after plant incubation in the dark (cf. a very low decrease in cold tolerance following the exposure to constant low <span class="hlt">hardening</span> temperature); a combination of high cold tolerance and high photochemical activity of the photosynthetic apparatus (cf. a low non-photochemical quenching at constant low <span class="hlt">hardening</span> temperature); and the capacity to rapidly increase cold tolerance in response to repeated short-term exposures to low <span class="hlt">hardening</span> temperature in plants grown outdoors (cf. a gradual increase after repeated exposure to constant low <span class="hlt">hardening</span> temperature). Possible methods underlying the plant response to daily short-term exposure to low temperature are proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040075896','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040075896"><span>Development of a Pressure-Dependent Constitutive Model with Combined Multilinear Kinematic and Isotropic <span class="hlt">Hardening</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Allen Phillip A.; Wilson, Christopher D.</p> <p>2003-01-01</p> <p>The development of a pressure-dependent constitutive model with combined multilinear kinematic and isotropic <span class="hlt">hardening</span> is presented. The constitutive model is developed using the ABAQUS user material subroutine (UMAT). First the pressure-dependent plasticity model is derived. Following this, the combined bilinear and combined multilinear <span class="hlt">hardening</span> equations are developed for von Mises plasticity theory. The <span class="hlt">hardening</span> rule equations are then modified to include pressure dependency. The method for implementing the new constitutive model into ABAQUS is given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6897611','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6897611"><span>Surface <span class="hlt">hardening</span> of steel by laser and electron beam. (Latest citations from METADEX). Published Search</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1994-09-01</p> <p>The bibliography contains citations concerning electron beam <span class="hlt">hardening</span> of steels and alloys. Among the materials surface <span class="hlt">hardened</span> are carbon and alloy steels, aircraft spur gears, nitrocarburized steel, turbine blades, titanium-carbon steel, titanium, and rolling bearings. Effect of transformation plasticity on residual stress fields in laser surface <span class="hlt">hardening</span> treatment is also examined. (Contains a minimum of 93 citations and includes a subject term index and title list.)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/381583','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/381583"><span>Surface <span class="hlt">hardening</span> of steel by laser and electron beam. (Latest citations from Metadex). Published Search</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p></p> <p>1996-08-01</p> <p>The bibliography contains citations concerning electron beam <span class="hlt">hardening</span> of steels and alloys. Among the materials surface <span class="hlt">hardened</span> are carbon and alloy steels, aircraft spur gears, nitrocarburized steel, turbine blades, titanium-carbon steel, titanium, and rolling bearings. Effect of transformation plasticity on residual stress fields in laser surface <span class="hlt">hardening</span> treatment is also examined.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA206127','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA206127"><span>A Combined Isotropic-Kinematic <span class="hlt">Hardening</span> Model for Large Deformation Metal Plasticity</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1988-12-01</p> <p>713C and Waspaloy, ASME Series D, 87, p. 275. 1965 WILSON, D.V., Reversible Work <span class="hlt">Hardening</span> in Alloys of Cubic Metals, Acta Metallurgica, 13, pp. 807-814...Sum m ary ............................................................ 32 3. Micromodeling of a Particle-<span class="hlt">Hardened</span> Alloy Using the Finite Element M...in a particle <span class="hlt">hardened</span> alloy is presented. A finite element model was used to model the effects of the particle-matrix interaction. The results</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8985010','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8985010"><span>Recalibrated Mariner 10 Color Mosaics: Implications for Mercurian <span class="hlt">Volcanism</span></span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Robinson; Lucey</p> <p>1997-01-10</p> <p>Recalibration of Mariner 10 color image data allows the identification of distinct color units on the mercurian surface. We analyze these data in terms of opaque mineral abundance, iron content, and <span class="hlt">soil</span> maturity and find color units consistent with the presence of <span class="hlt">volcanic</span> deposits on Mercury's surface. Additionally, materials associated with some impact craters have been excavated from a layer interpreted to be deficient in opaque minerals within the crust, possibly analogous to the lunar anorthosite crust. These observations suggest that Mercury has undergone complex differentiation like the other terrestrial planets and the Earth's moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020041','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020041"><span>Recalibrated mariner 10 color mosaics: Implications for mercurian <span class="hlt">volcanism</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Robinson, M.S.; Lucey, P.G.</p> <p>1997-01-01</p> <p>Recalibration of Mariner 10 color image data allows the identification of distinct color units on the mercurian surface. We analyze these data in terms of opaque mineral abundance, iron content, and <span class="hlt">soil</span> maturity and find color units consistent with the presence of <span class="hlt">volcanic</span> deposits on Mercury's surface. Additionally, materials associated with some impact craters have been excavated from a layer interpreted to be deficient in opaque minerals within the crust, possibly analogous to the lunar anorthosite crust. These observations suggest that Mercury has undergone complex differentiation like the other terrestrial planets and the Earth's moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1581.1307S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1581.1307S"><span>Case depth verification of <span class="hlt">hardened</span> samples with Barkhausen noise sweeps</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Santa-aho, Suvi; Hakanen, Merja; Sorsa, Aki; Vippola, Minnamari; Leiviskä, Kauko; Lepistö, Toivo</p> <p>2014-02-01</p> <p>An interesting topic of recent Barkhausen noise (BN) method studies is the application of the method to case depth evaluation of <span class="hlt">hardened</span> components. The utilization of BN method for this purpose is based on the difference in the magnetic properties between the <span class="hlt">hardened</span> case and the soft core. Thus, the detection of case depth with BN can be achieved. The measurements typically have been carried out by using low magnetizing frequencies which have deeper penetration to the ferromagnetic samples than the conventional BN measurement. However, the penetration depth is limited due to eddy current damping of the signal. We introduce here a newly found sweep measurement concept for the case depth evaluation. In this study sweep measurements were carried out with various magnetizing frequencies and magnetizing voltages to detect the effect of different frequency and voltage and their correspondence to the actual case depth values verified from destructive characterization. Also a BN measurement device that has an implemented sweep analysis option was utilised. The samples were either induction or case-<span class="hlt">hardened</span> samples and sample geometry contained both rod samples and gear axle samples with different case depth values. Samples were also further characterized with Xray diffraction to study the residual stress state of the surface. The detailed data processing revealed that also other calculated features than the maximum slope division of the 1st derivative of the BN signal could hold the information about the case depth value of the samples. The sweep method was able to arrange the axles into correct order according to the case depth value even though the axles were used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8360199','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8360199"><span>Organoapatites: materials for artificial bone. II. <span class="hlt">Hardening</span> reactions and properties.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stupp, S I; Mejicano, G C; Hanson, J A</p> <p>1993-03-01</p> <p>This article reports on chemical reactions and the properties they generated in artificial bone materials termed "organoapatites." These materials are synthesized using methodology we reported in the previous article of this series. Two different processes were studied here for the transition from organoapatite particles to implants suitable for the restoration of the skeletal system. One process involved the <span class="hlt">hardening</span> of powder compacts by beams of blue light derived from a lamp or a laser and the other involved pressure-induced interdiffusion of polymers. In both cases, the <span class="hlt">hardening</span> reaction involved the formation of a polyion complex between two polyelectrolytes. In the photo-induced reaction an anionic electrolyte polymerizes to form the coulombic network and in the pressure-induced one, pressure forms the complex by interdiffusion of two polyions. Model reactions were studied using various polycations. Based on these results the organoapatite selected for the study was that containing dispersed poly(L-lysine) and sodium acrylate as the anionic monomer. The organomineral particles can be pressed at room temperature into objects of great physical integrity and hydrolytic stability relative to anorganic controls. The remarkable fact about these objects is that intimate molecular dispersion of only 2-3% by weight organic material provides integrity to the mineral network in an aqueous medium and also doubles its tensile strength. This integrity is essentially nonexistent in "anorganic" samples prepared by the same methodology used in organoapatite synthesis. The improvement in properties was most effectively produced by molecular bridges formed by photopolymerization. The photopolymerization leads to the "<span class="hlt">hardening</span>" of pellets prepared by pressing of organoapatite powders. The reaction was found to be more facile in the microstructure of the organomineral, and it is potentially useful in the surgical application of organoapatites as artificial bone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/9468','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/9468"><span>BUSFET - A Novel Radiation-<span class="hlt">Hardened</span> SOI Transistor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schwank, J.R.; Shaneyfelt, M.R.; Draper, B.L.; Dodd, P.E.</p> <p>1999-07-20</p> <p>The total-dose hardness of SOI technology is limited by radiation-induced charge trapping in gate, field, and SOI buried oxides. Charge trapping in the buried oxide can lead to back-channel leakage and makes <span class="hlt">hardening</span> SOI transistors more challenging than <span class="hlt">hardening</span> bulk-silicon transistors. Two avenues for <span class="hlt">hardening</span> the back-channel are (1) to use specially prepared SOI buried oxides that reduce the net amount of trapped positive charge or (2) to design transistors that are less sensitive to the effects of trapped charge in the buried oxide. In this work, we propose a new partially-depleted SOI transistor structure that we call the BUSFET--Body Under Source FET. The BUSFET utilizes a shallow source and a deep drain. As a result, the silicon depletion region at the back channel caused by radiation-induced charge trapping in the buried oxide does not form a conducting path between source and drain. Thus, the BUSFET structure design can significantly reduce radiation-induced back-channel leakage without using specially prepared buried oxides. Total dose hardness is achieved without degrading the intrinsic SEU and dose rate hardness of SOI technology. The effectiveness of the BUSFET structure for reducing total-dose back-channel leakage depends on several variables, including the top silicon film thickness and doping concentration and the depth of the source. 3-D simulations show that for a doping concentration of 10{sup 18} cm{sup {minus}3} and a source depth of 90 nm, a silicon film thickness of 180 nm is sufficient to almost completely eliminate radiation-induced back-channel leakage. However, for a doping concentration of 3x10{sup 17} cm{sup {minus}3}, a thicker silicon film (300 nm) must be used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JAP....90..882G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JAP....90..882G"><span>Bulk-<span class="hlt">hardened</span> magnets based on Y2Co17</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gabay, A. M.; Zhang, Y.; Hadjipanayis, G. C.</p> <p>2001-07-01</p> <p>Bulk magnetic <span class="hlt">hardening</span> of cast Y2Co17-based alloys was systematically studied for different compositions and heat treatments. Additions of Cu and Zr, Hf, or Ti to the Y-Co were found to be essential for developing coercivity. The performance of Y-Co-Cu-Zr magnets can be significantly improved by partial Pr and Fe substitutions for Y and Co, respectively. Anisotropic (Y0.8Pr0.2)11.5Zr2.75Co56.75Fe14Cu15 powders with intrinsic coercivity of 7.8 kOe and energy product of 14.4 MG Oe were obtained after annealing at 900 °C for 15 min and cooling to 200 °C at the rate of 4 °C/min. We also explored the effects of some other rare earths (La, Nd, Gd) and transition metals (Mn, Ni) on the magnetic properties of the Y-Co-Cu-Zr magnets. The phases present and the microstructure were analyzed with x-ray diffraction, thermomagnetic analysis, and transmission electron microscopy. The cellular/lamellar microstructure of the bulk-<span class="hlt">hardened</span> alloys is similar to that of Sm-Co-Cu-Zr magnets. Among the most noticeable distinctions in the Y-Co-Cu-Zr alloys are a smaller average size of 2:17 cells and a variety of Zr-rich phases, like Zr2Co11 and Zr6Co23. Although the Y2Co17 phase is known to have an "easy-plane" anisotropy, the x-ray diffraction experiments with magnetically oriented powders suggest that in the bulk-<span class="hlt">hardened</span> Y-Co-Cu-Zr and Y-Co-Cu-Fe-Zr magnets the 2:17 phase has uniaxial anisotropy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22263745','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22263745"><span>Case depth verification of <span class="hlt">hardened</span> samples with Barkhausen noise sweeps</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Santa-aho, Suvi; Vippola, Minnamari; Lepistö, Toivo; Hakanen, Merja; Sorsa, Aki; Leiviskä, Kauko</p> <p>2014-02-18</p> <p>An interesting topic of recent Barkhausen noise (BN) method studies is the application of the method to case depth evaluation of <span class="hlt">hardened</span> components. The utilization of BN method for this purpose is based on the difference in the magnetic properties between the <span class="hlt">hardened</span> case and the soft core. Thus, the detection of case depth with BN can be achieved. The measurements typically have been carried out by using low magnetizing frequencies which have deeper penetration to the ferromagnetic samples than the conventional BN measurement. However, the penetration depth is limited due to eddy current damping of the signal. We introduce here a newly found sweep measurement concept for the case depth evaluation. In this study sweep measurements were carried out with various magnetizing frequencies and magnetizing voltages to detect the effect of different frequency and voltage and their correspondence to the actual case depth values verified from destructive characterization. Also a BN measurement device that has an implemented sweep analysis option was utilised. The samples were either induction or case-<span class="hlt">hardened</span> samples and sample geometry contained both rod samples and gear axle samples with different case depth values. Samples were also further characterized with Xray diffraction to study the residual stress state of the surface. The detailed data processing revealed that also other calculated features than the maximum slope division of the 1st derivative of the BN signal could hold the information about the case depth value of the samples. The sweep method was able to arrange the axles into correct order according to the case depth value even though the axles were used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1993/0445/pdf/of1993-0445.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1993/0445/pdf/of1993-0445.pdf"><span>Can rain cause <span class="hlt">volcanic</span> eruptions?</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mastin, Larry G.</p> <p>1993-01-01</p> <p><span class="hlt">Volcanic</span> eruptions are renowned for their violence and destructive power. This power comes ultimately from the heat and pressure of molten rock and its contained gases. Therefore we rarely consider the possibility that meteoric phenomena, like rainfall, could promote or inhibit their occurrence. Yet from time to time observers have suggested that weather may affect <span class="hlt">volcanic</span> activity. In the late 1800's, for example, one of the first geologists to visit the island of Hawaii, J.D. Dana, speculated that rainfall influenced the occurrence of eruptions there. In the early 1900's, volcanologists suggested that some eruptions from Mount Lassen, Calif., were caused by the infiltration of snowmelt into the volcano's hot summit. Most such associations have not been provable because of lack of information; others have been dismissed after careful evaluation of the evidence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984EOSTr..65Q.137B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984EOSTr..65Q.137B"><span>Venus <span class="hlt">volcanism</span> and El Chichon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bell, Peter M.</p> <p></p> <p>Reinterpretations of telemetry data returned to earth from the Pioneer Venus Orbiter suggest that the surface of Venus may be characterized by violent immense <span class="hlt">volcanic</span> activity. L.W. Esposito has made an interactive analysis of Pioneer ultraviolet spectral data and similar data from the earth's atmosphere [Science, 223, 1072-1074, 1984]. Spacecraft analysis of sulfur dioxide in the earth's upper atmosphere, apparently released by El Chich[acu]on, Mexico, in March 1982 (EOS, June 14, 1983, p. 411, and August 16, 1983, p. 506) prompted reanalysis of accumulated Pioneer ultraviolet data. Massive injections of sulfur dioxide into the Venus atmosphere could be the result of <span class="hlt">volcanic</span> eruptions about the size of the Krakatoa explosive eruption that took place between Java and Summatra in 1883.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17792942','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17792942"><span>Recent <span class="hlt">volcanism</span> and the stratosphere.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cronin, J F</p> <p>1971-05-21</p> <p>In the quiet years after the 1956 eruption of the Bezymianny volcano in central Kamchatka, it is doubtful that any volcano vented into the stratosphere until the 1963 eruptions of Agung (Bali), Trident (Alaska), and Surtsey (Iceland). From 1963 to the Hekla (Iceland) event in May 1970, two latitudinal belts of volcanoes have ejected ash and gases into the stratosphere. One belt is equatorial and the other is just below the Arctic Circle. The latter, where the tropopause is considerably lower, may have been the principal source of replenishment of <span class="hlt">volcanic</span> dust and gases to the stratosphere. Submarine and phreatic <span class="hlt">volcanic</span> eruptions may have been the sources of reported increase of water vapor in the stratosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70112305','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70112305"><span>Satellite observation of effusive <span class="hlt">volcanism</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Williams, R.S.; Friedman, J.D.</p> <p>1970-01-01</p> <p>Infrared emission from an active effusive <span class="hlt">volcanic</span> eruption on Surtsey, Vestmannaeyjar, Iceland, was recorded by airborne and satellite infrared systems at irregular intervals between 19 August and 3 October 1966. Ground and lava temperature measurements and volumetric lava outflow data permitted a comparison to be made between total thermal-energy yield and radiant emission recorded by the satellite system. The Nimbus HRIR recorded radiant emission at a level of about 3% of the estimated total thermal yield.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://rock.geosociety.org/Store/detail.aspx?id=SPE412','USGSPUBS'); return false;" href="http://rock.geosociety.org/Store/detail.aspx?id=SPE412"><span><span class="hlt">Volcanic</span> hazards in Central America</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rose, William I.; Bluth, Gregg J.S.; Carr, Michael J.; Ewert, John W.; Patino, Lina C.; Vallance, James W.</p> <p>2006-01-01</p> <p>This volume is a sampling of current scientific work about volcanoes in Central America with specific application to hazards. The papers reflect a variety of international and interdisciplinary collaborations and employ new methods. The book will be of interest to a broad cross section of scientists, especially volcanologists. The volume also will interest students who aspire to work in the field of volcano hazards mitigation or who may want to work in one of Earth’s most <span class="hlt">volcanically</span> active areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910023310','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910023310"><span><span class="hlt">Hardening</span> communication ports for survival in electrical overstress environments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Clark, O. Melville</p> <p>1991-01-01</p> <p>Greater attention is being focused on the protection of data I/O ports since both experience and lab tests have shown that components at these locations are extremely vulnerable to electrical overstress (EOS) in the form of transient voltages. Lightning and electrostatic discharge (ESD) are the major contributors to these failures; however, these losses can be prevented. <span class="hlt">Hardening</span> against transient voltages at both the board level and system level has a proven record of improving reliability by orders of magnitude. The EOS threats, typical failure modes, and transient voltage mitigation techniques are reviewed. Case histories are also reviewed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22412601','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22412601"><span>Ductility and work <span class="hlt">hardening</span> in nano-sized metallic glasses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chen, D. Z.; Gu, X. W.; An, Q.; Goddard, W. A.; Greer, J. R.</p> <p>2015-02-09</p> <p>In-situ nano-tensile experiments on 70 nm-diameter free-standing electroplated NiP metallic glass nanostructures reveal tensile true strains of ∼18%, an amount comparable to compositionally identical 100 nm-diameter focused ion beam samples and ∼3 times greater than 100 nm-diameter electroplated samples. Simultaneous in-situ observations and stress-strain data during post-elastic deformation reveal necking and work <span class="hlt">hardening</span>, features uncharacteristic for metallic glasses. The evolution of free volume within molecular dynamics-simulated samples suggests a free surface-mediated relaxation mechanism in nano-sized metallic glasses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740029898&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHardening','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740029898&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHardening"><span>Substorm effects in auroral spectra. [electron spectrum <span class="hlt">hardening</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eather, R. H.; Mende, S. B.</p> <p>1973-01-01</p> <p>A substorm time parameter is defined and used to order a large body of photometric data obtained on aircraft expeditions at high latitudes. The statistical analysis demonstrates <span class="hlt">hardening</span> of the electron spectrum at the time of substorm, and it is consistent with the accepted picture of poleward expansion of aurora at the time of substorm and curvature drift of substorm-injected electrons. These features are not evident from a similar analysis in terms of magnetic time. We conclude that the substorm time concept is a useful ordering parameter for auroral data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5899946','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5899946"><span>Approximating the dynamic response of strain-<span class="hlt">hardening</span> structures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Youngdahl, C.K.</p> <p>1991-01-01</p> <p>A mode approximation method is being developed to predict the dynamic plastic deformation of strain-<span class="hlt">hardening</span> structures. A mode shape having time-dependent coefficients is based on quasi-static deformation profiles. Two stress fields are associated with the modal shape, one satisfying the dynamic relations and the other satisfying the constitutive equations. The application of suitable matching conditions results in a set of simultaneous differential and algebraic equations for the amplitude coefficients and plastic region size. Using the example of a simply supported beam, the effect of varying the number of matching conditions on the accuracy of the solution is presented. 5 refs., 7 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995MMTA...26...21F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995MMTA...26...21F"><span>The effect of niobium on the <span class="hlt">hardenability</span> of microalloyed austenite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fossaert, C.; Rees, G.; Maurickx, T.; Bhadeshia, H. K. D. H.</p> <p>1995-01-01</p> <p>The powerful effect that varying the extent of niobium-carbide dissolution has on the “hardenability” of microalloyed austenite is demonstrated using dilatometric measurement of the critical cooling rate required to from microstructures containing >95 Pct martensite. The results can be rationalized on the hypothesis that the <span class="hlt">hardenability</span> of austenite is enhanced by niobium in solid solution, possibly by its segregation to austenite grain boundaries, but is decreased by precipitation of niobium-carbide particles. This effect appears analogous to that of boron in steels and is found to be independent of variations in the austenite grain size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/64278','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/64278"><span>Structural influences on the work <span class="hlt">hardening</span> behavior of aluminum</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chu, David</p> <p>1994-12-01</p> <p>Effects of various grain and subgrain morphologies on low temperature work <span class="hlt">hardening</span> of pure Al is studied using tensile tests. Plotting the work <span class="hlt">hardening</span> rate as a function of true stress, the work <span class="hlt">hardening</span> is separable into two distinct regimes. Both regimes are approximated by a line θ = θ<sub>0</sub> - K<sub>2</sub>σ, where θ<sub>0</sub> is theoretical work <span class="hlt">hardening</span> rate at zero stress and K<sub>2</sub> is related to dynamic recovery rate. The first or early deformation regime exhibits greater values of θ<sub>0</sub> and K<sub>2</sub> and can extend up to the first 10% strain of tensile deformation. This early deformation regime is contingent on the existence of a pre-existent dislocation substructure from previous straining. The θ<sub>0</sub> and K<sub>2</sub> associated with the early deformation regime are dependent on the strength and orientation of the pre-existent dislocation substructure relative to the new strain path. At high enough temperatures, this pre-existent dislocation substructure is annealed out, resulting in the near elimination of the early deformation regime. In comparison, the latter regime is dominated by the initial grain and/or subgrain morphology and exhibit lower values of θ<sub>0</sub> and K<sub>2</sub>. The actual value of K<sub>2</sub> in the latter regime is strongly dependent on the existence of a subgrain morphology. Recrystallized or well-annealed microstructures exhibit greater values of K<sub>2</sub> than microstructures that remain partially or fully unrecrystallized. The higher K<sub>2</sub> value is indicative of a more rapid dynamic recovery rate and a greater degree of strain relaxation. The ability to achieve a more relaxed state produces a low-energy cellular dislocation substructure upon deformation. The introduction of subgrains hinders the evolution of a low-energy dislocation cell network, giving way to a more random distribution of the dislocation density.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA282123','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA282123"><span>Stochastic Analysis of Facilities <span class="hlt">Hardened</span> Against Conventional Weapons Effects</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1994-05-01</p> <p>called FAST Ill was completed which modeled various elements of the <span class="hlt">hardened</span> or strategic systems failure problem (Rowan, 1977). Failure Analysis by...later date. If the system is modeled as a general beamn the equation of motion of the system can be written as m + pAv,, = q.(xt) (3.5) where the comma...3.6 into equation 3.5 rermsm: (1 -AdM,= + Ao~v,= + pAv,,, = q,,(xt) (3.7) The term q.xt) represents the load model input to the system . The hystertc</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhPro..56.1083B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhPro..56.1083B"><span>Development of a Flexible Laser <span class="hlt">Hardening</span> & Machining Center and Proof of Concept on C-45 Steel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bouquet, Jan; Van Camp, Dries; Vanhove, Hans; Clijsters, Stijn; Amirahmad, Mohammadi; Lauwers, Bert</p> <p></p> <p>The production of <span class="hlt">hardened</span> precision parts is conventionally done in 3 steps. Rough machining of a workpiece in soft stage is followed by a <span class="hlt">hardening</span> step, usually a batch process, and finalized by a hard machining finishing step. To omit the inevitable time delay and loss of accuracy because of part re-clamping, these steps should be incorporated within one flexible machining center. This paper describes the development of this machining center which allowsmachining and laser <span class="hlt">hardening</span> in one setup, followed by a proof of concept for <span class="hlt">hardening</span> C45 steel on this setup.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920042208&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHardening','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920042208&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHardening"><span><span class="hlt">Hardening</span> mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miner, R. V.; Castelli, M. G.</p> <p>1992-01-01</p> <p>The relative contributions of the <span class="hlt">hardening</span> mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to <span class="hlt">hardening</span>, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic <span class="hlt">hardening</span>. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic <span class="hlt">hardening</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17211802','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17211802"><span>Consequences of heat <span class="hlt">hardening</span> on a field fitness component in Drosophila depend on environmental temperature.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Loeschcke, Volker; Hoffmann, Ary A</p> <p>2007-02-01</p> <p>Heat <span class="hlt">hardening</span> increases thermal resistance to more extreme temperatures in the laboratory. However, heat <span class="hlt">hardening</span> also has negative consequences, and the net benefit of <span class="hlt">hardening</span> has not been evaluated in the field. We tested short-term heat <span class="hlt">hardening</span> effects on the likelihood of Drosophila melanogaster to be caught at different temperatures at baits in field sites without natural resources. We predicted that <span class="hlt">hardened</span> flies should be more frequently caught at the baits at high but not low temperatures. Under cool conditions, flies <span class="hlt">hardened</span> at 36 degrees C, and to a lesser extent at 34 degrees C, were less frequently caught at baits than nonhardened flies a few hours after release, indicating a negative effect of <span class="hlt">hardening</span>. In later captures, negative effects tended to disappear, particularly in males. Under warm conditions, there was an overall balance of negative and positive effects, though with a different temporal resolution. Under very hot conditions, when capture rates were low, there was a large benefit of <span class="hlt">hardening</span> at 36 degrees C and 34 degrees C but not 33 degrees C. Finally, based on climatic records, the overall benefit of <span class="hlt">hardening</span> in D. melanogaster is discussed as an evolved response to high temperatures occasionally experienced by organisms at some locations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1812509M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1812509M"><span>Hydrothermal activity and subsurface <span class="hlt">soil</span> complexity: implication for outgassing processes at Solfatara crater, Campi Flegrei caldera</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Montanaro, Cristian; Mayer, Klaus; Scheu, Bettina; Isaia, Roberto; Mangiacapra, Annarita; Gresse, Marceau; Vandemeulebrouck, Jean; Moretti, Roberto; Dingwell, Donald B.</p> <p>2016-04-01</p> <p>The Solfatara area and its fumaroles are the main surface phenomena of the vigorous hydrothermal activity within the active Campi Flegrei caldera system. The existing fault system appears to have a major control on outgassing which in turn leads to a strong alteration of the <span class="hlt">volcanic</span> products. Moreover the maar-nature of the crater, and its filling by more recent <span class="hlt">volcanic</span> deposits, resulted in a complex fractured and multilayered cap to the rising gases. As a consequence the hydrothermal alteration differently affects the rocks within the crater, including pyroclastic fallout ash beds, pyroclastic density current deposits, breccias and lavas. The induced changes in both original microstructure and physical and mechanical properties of the rocks control the outgassing behavior. Here, we report results from a measurement survey conducted in July 2015, and aimed to characterize the in-situ physical (temperature, humidity) and mechanical (permeability, strength, stiffness) properties. The survey also included a mapping of the surficial hydrothermal features and their distributions. Chemical analyses and laboratory measurements (porosity, granulometry) of selected samples were additionally performed. Results show that the crater floor area comprises very different kinds of <span class="hlt">soils</span>, from fine grained, thin laminated deposits around the two bubbling Fangaia mud pools, to crusted hummock formations along the SE and NE border of the crater. Dry and solid alunite-rich deposits are present in the western and southern part. Furthermore we observed evidences of a beginning of crust formation within the central part of the crater. A large range of surface temperatures, from boiling point to ambient temperature, were measured throughout the surveyed area. Outgassing occurs mainly along the crack system, which has also generated the crusted hummocks. Elsewhere the fluid circulation in the subsoil is favored by the presence of coarse and highly porous sulfur-<span class="hlt">hardened</span> levels, whereas</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996JGR...10113805M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996JGR...10113805M"><span>Scaled experiments of <span class="hlt">volcanic</span> spreading</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Merle, Olivier; Borgia, Andrea</p> <p>1996-06-01</p> <p>Experiments were conducted to study the spreading of <span class="hlt">volcanic</span> constructs. Volcanoes are simulated by a sand cone, and the <span class="hlt">volcanic</span> substratum is simulated by a sand layer (brittle substratum) overlying a silicone layer (ductile substratum). Similarity conditions between natural volcanoes and experimental prototypes led to the definition of dimensionless π numbers. Experiments determine π values which predict whether or not spreading takes place. Of particular importance are the ratio between the thickness of the brittle substratum and the height of the volcano (π2) and the brittle/ductile ratio of the substratum (π3). π2 indicates that the volcano must be large enough to "break" the substratum before spreading occurs, whereas π3 controls the style of deformation. During spreading, these dimensionless numbers change with time, reaching values that tend toward those observed for stable configurations. Experimental values are compared with those from well-constrained natural examples. It is found that an essential requirement for <span class="hlt">volcanic</span> spreading is the presence of a low-viscosity layer within the substratum. Flow of the weak layer away from the excess load is responsible for the spreading. The overlying edifice displays radial intersecting grabens, due to concentric stretching, dissected summit areas; concentric zones of thrusts and folds form in the substratum around the edifice, and diapirs of the ductile substratum rise within the fault zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NW....100..739R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NW....100..739R"><span><span class="hlt">Volcanic</span> mercury in Pinus canariensis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodríguez Martín, José Antonio; Nanos, Nikos; Miranda, José Carlos; Carbonell, Gregoria; Gil, Luis</p> <p>2013-08-01</p> <p>Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. <span class="hlt">Volcanic</span> emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to <span class="hlt">volcanic</span> activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg-1) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg-1). Thus, mercury emissions originating from the eruption remained only as a mark—in pyroclastic wounds—and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg-1) and bark (6.0 μg kg-1) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in <span class="hlt">volcanism</span>-adapted species.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6427712','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6427712"><span>Source mechanism of <span class="hlt">volcanic</span> tremor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ferrick, M.G.; Qamar, A.; St. Lawrence, W.F.</p> <p>1982-10-10</p> <p>Low-frequency (<10 Hz) <span class="hlt">volcanic</span> earthquakes originate at a wide range of depths and occur before, during, and after magmatic eruptions. The characteristics of these earthquakes suggest that they are not typical tectonic events. Physically analogous processes occur in hydraulic fracturing of rock formations, low-frequency icequakes in temperate glaciers, and autoresonance in hydroelectric power stations. We propose that unsteady fluid flow in <span class="hlt">volcanic</span> conduits is the common source mechanism of low-frequency <span class="hlt">volcanic</span> earthquakes (tremor). The fluid dynamic source mechanism explains low-frequency earthquakes of arbitrary duration, magnitude, and depth of origin, as unsteady flow is independent of physical properties of the fluid and conduit. Fluid transients occur in both low-viscosity gases and high-viscosity liquids. A fluid transient analysis can be formulated as generally as is warranted by knowledge of the composition and physical properties of the fluid, material properties, geometry and roughness of the conduit, and boundary conditions. To demonstrate the analytical potential of the fluid dynamic theory, we consider a single-phase fluid, a melt of Mount Hood andesite at 1250/sup 0/C, in which significant pressure and velocity variations occur only in the longitudinal direction. Further simplification of the conservation of mass and momentum equations presents an eigenvalue problem that is solved to determine the natural frequencies and associated damping of flow and pressure oscillations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5161658','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5161658"><span>Disruptive event analysis: <span class="hlt">volcanism</span> and igneous intrusion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Crowe, B.M.</p> <p>1980-08-01</p> <p>An evaluation is made of the disruptive effects of <span class="hlt">volcanic</span> activity with respect to long term isolation of radioactive waste through deep geologic storage. Three major questions are considered. First, what is the range of disruption effects of a radioactive waste repository by <span class="hlt">volcanic</span> activity. Second, is it possible, by selective siting of a repository, to reduce the risk of disruption by future <span class="hlt">volcanic</span> activity. And third, can the probability of repository disruption by <span class="hlt">volcanic</span> activity be quantified. The main variables involved in the evaluation of the consequences of repository disruption by <span class="hlt">volcanic</span> activity are the geometry of the magma-repository intersection (partly controlled by depth of burial) and the nature of <span class="hlt">volcanism</span>. Potential radionuclide dispersal by <span class="hlt">volcanic</span> transport within the biosphere ranges in distance from several kilometers to global. Risk from the most catastrophic types of eruptions can be reduced by careful site selection to maximize lag time prior to the onset of activity. Certain areas or <span class="hlt">volcanic</span> provinces within the western United States have been sites of significant <span class="hlt">volcanism</span> and should be avoided as potential sites for a radioactive waste repository. Examples of projection of future sites of active <span class="hlt">volcanism</span> are discussed for three areas of the western United States. Probability calculations require two types of data: a numerical rate or frequency of <span class="hlt">volcanic</span> activity and a numerical evaluation of the areal extent of <span class="hlt">volcanic</span> disruption for a designated region. The former is clearly beyond the current state of art in volcanology. The latter can be approximated with a reasonable degree of satisfaction. In this report, simplified probability calculations are attempted for areas of past <span class="hlt">volcanic</span> activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/3448312','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3448312"><span>[Study of mutagenicity of epoxy resin <span class="hlt">hardeners</span> by fluctuation test].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hayashi, K; Koike, N; Mashizu, N; Mozawa, K; Sakaba, H; Shimizu, H</p> <p>1987-11-01</p> <p>Mutagenicity of nine epoxy resin <span class="hlt">hardeners</span> was examined by a fluctuation test modified by Gatehouse. The test was performed by using Salmonella typhimurium TA98 with a metabolic activation system. In our laboratory, the results of the fluctuation test were compared with the results obtained by the previously mentioned Ames preincubation method. Six out of nine epoxy resin <span class="hlt">hardeners</span> showed mutagenic activity in both the fluctuation test and Ames preincubation method, but one out of the nine was negative in both test systems. Two out of the nine were positive by either of the two testing systems. The fluctuation test is disadvantageous in that it is marginally slower and requires slightly more labor than the Ames test and furthermore it is difficult to increase the amount of microsome because of background interference. These disadvantages, however, are somewhat offset by the advantages that small organs such as urinary bladder can be used instead of liver cells and that a small amount of microsome can be employed for metabolic activation. This test is also suitable for testing aqueous samples containing low levels of mutagen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19048797','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19048797"><span>Quantifying characters: polygenist anthropologists and the <span class="hlt">hardening</span> of heredity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hume, Brad D</p> <p>2008-01-01</p> <p>Scholars studying the history of heredity suggest that during the 19th-century biologists and anthropologists viewed characteristics as a collection of blended qualities passed on from the parents. Many argued that those characteristics could be very much affected by environmental circumstances, which scholars call the inheritance of acquired characteristics or "soft" heredity. According to these accounts, Gregor Mendel reconceived heredity--seeing distinct hereditary units that remain unchanged by the environment. This resulted in particular traits that breed true in succeeding generations, or "hard" heredity. The author argues that polygenist anthropology (an argument that humanity consisted of many species) and anthropometry in general should be seen as a <span class="hlt">hardening</span> of heredity. Using a debate between Philadelphia anthropologist and physician, Samuel G. Morton, and Charleston naturalist and reverend, John Bachman, as a springboard, the author contends that polygenist anthropologists <span class="hlt">hardened</span> heredity by conceiving of durable traits that might reappear even after a race has been eliminated. Polygenists saw anthropometry (the measurement of humans) as one method of quantifying hereditary qualities. These statistical ranges were ostensibly characteristics that bred true and that defined racial groups. Further, Morton's interest in hybridity and racial mixing demonstrates that the polygenists focused as much on the transmission and recognition of "amalgamations" of characters as they did on racial categories themselves. The author suggests that seeing race science as the study of heritable, statistical characteristics rather than broad categories helps explain why "race" is such a persistent cultural phenomenon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012301','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012301"><span>Folding and faulting of strain-<span class="hlt">hardening</span> sedimentary rocks</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Johnson, A.M.</p> <p>1980-01-01</p> <p>The question of whether single- or multi-layers of sedimentary rocks will fault or fold when subjected to layer-parallel shortening is investigated by means of the theory of elastic-plastic, strain-<span class="hlt">hardening</span> materials, which should closely describe the properties of sedimentary rocks at high levels in the Earth's crust. The most attractive feature of the theory is that folding and faulting, intimately related in nature, are different responses of the same idealized material to different conditions. When single-layers of sedimentary rock behave much as strain-<span class="hlt">hardening</span> materials they are unlikely to fold, rather they tend to fault, because contrasts in elasticity and strength properties of sedimentary rocks are low. Amplifications of folds in such materials are negligible whether contacts between layer and media are bonded or free to slip for single layers of dolomite, limestone, sandstone, or siltstone in media of shale. Multilayers of these same rocks fault rather than fold if contacts are bonded, but they fold readily if contacts between layers are frictionless, or have low yield strengths, for example due to high pore-water pressure. Faults may accompany the folds, occurring where compression is increased in cores of folds. Where there is predominant reverse faulting in sedimentary sequences, there probably were few structural units. ?? 1980.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21305005','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21305005"><span>DISCREPANT <span class="hlt">HARDENING</span> OBSERVED IN COSMIC-RAY ELEMENTAL SPECTRA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ahn, H. S.; Ganel, O.; Han, J. H.; Kim, K. C.; Lee, M. H.; Lutz, L.; Malinin, A.; Allison, P.; Beatty, J. J.; Bagliesi, M. G.; Bigongiari, G.; Maestro, P.; Marrocchesi, P. S.; Childers, J. T.; DuVernois, M. A.; Conklin, N. B.; Coutu, S.; Mognet, S. I.; Jeon, J. A.; Minnick, S.</p> <p>2010-05-01</p> <p>The balloon-borne Cosmic Ray Energetics And Mass experiment launched five times from Antarctica has achieved a cumulative flight duration of about 156 days above 99.5% of the atmosphere. The instrument is configured with complementary and redundant particle detectors designed to extend direct measurements of cosmic-ray composition to the highest energies practical with balloon flights. All elements from protons to iron nuclei are separated with excellent charge resolution. Here, we report results from the first two flights of {approx}70 days, which indicate <span class="hlt">hardening</span> of the elemental spectra above {approx}200 GeV/nucleon and a spectral difference between the two most abundant species, protons and helium nuclei. These results challenge the view that cosmic-ray spectra are simple power laws below the so-called knee at {approx}10{sup 15} eV. This discrepant <span class="hlt">hardening</span> may result from a relatively nearby source, or it could represent spectral concavity caused by interactions of cosmic rays with the accelerating shock. Other possible explanations should also be investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/281702','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/281702"><span>A radiation-<span class="hlt">hardened</span>, computer for satellite applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gaona, J.I. Jr.</p> <p>1996-08-01</p> <p>This paper describes high reliability radiation <span class="hlt">hardened</span> computers built by Sandia for application aboard DOE satellite programs requiring 32 bit processing. The computers highlight a radiation <span class="hlt">hardened</span> (10 kGy(Si)) R3000 executing up to 10 million reduced instruction set instructions (RISC) per second (MIPS), a dual purpose module control bus used for real-time default and power management which allows for extended mission operation on as little as 1.2 watts, and a local area network capable of 480 Mbits/s. The central processing unit (CPU) is the NASA Goddard R3000 nicknamed the ``Mongoose or Mongoose 1``. The Sandia Satellite Computer (SSC) uses Rational`s Ada compiler, debugger, operating system kernel, and enhanced floating point emulation library targeted at the Mongoose. The SSC gives Sandia the capability of processing complex types of spacecraft attitude determination and control algorithms and of modifying programmed control laws via ground command. And in general, SSC offers end users the ability to process data onboard the spacecraft that would normally have been sent to the ground which allows reconsideration of traditional space-grounded partitioning options.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1035832','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1035832"><span>Dislocation Starvation and Exhaustion <span class="hlt">Hardening</span> in Mo-alloy Nanofibers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chisholm, Claire; Bei, Hongbin; Lowry, M. B.; Oh, Jason; Asif, S.A. Syed; Warren, O.; Shan, Zhiwei; George, Easo P; Minor, Andrew</p> <p>2012-01-01</p> <p>The evolution of defects in Mo alloy nanofibers with initial dislocation densities ranging from 0 to 1.6 1014 m2 were studied using an in situ push-to-pull device in conjunction with a nanoindenter in a transmission electron microscope. Digital image correlation was used to determine stress and strain in local areas of deformation. When they had no initial dislocations the Mo alloy nanofibers suffered sudden catastrophic elongation following elastic deformation to ultrahigh stresses. At the other extreme fibers with a high dislocation density underwent sustained homogeneous deformation after yielding at much lower stresses. Between these two extremes nanofibers with intermediate dislocation densities demonstrated a clear exhaustion <span class="hlt">hardening</span> behavior, where the progressive exhaustion of dislocations and dislocation sources increases the stress required to drive plasticity. This is consistent with the idea that mechanical size effects ( smaller is stronger ) are due to the fact that nanostructures usually have fewer defects that can operate at lower stresses. By monitoring the evolution of stress locally we find that exhaustion <span class="hlt">hardening</span> causes the stress in the nanofibers to surpass the critical stress predicted for self-multiplication, supporting a plasticity mechanism that has been hypothesized to account for the rapid strain softening observed in nanoscale bcc materials at high stresses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1327659-irradiation-hardening-pure-tungsten-exposed-neutron-irradiation','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1327659-irradiation-hardening-pure-tungsten-exposed-neutron-irradiation"><span>Irradiation <span class="hlt">hardening</span> of pure tungsten exposed to neutron irradiation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; ...</p> <p>2016-08-26</p> <p>In this paper, pure tungsten samples have been neutron irradiated in HFIR at 90–850 °C to 0.03–2.2 dpa. A dispersed barrier <span class="hlt">hardening</span> model informed by the available microstructure data has been used to predict the hardness. Comparison of the model predictions and the measured Vickers hardness reveals the dominant <span class="hlt">hardening</span> contribution at various irradiation conditions. For tungsten samples irradiated in HFIR, the results indicate that voids and dislocation loops contributed to the hardness increase in the low dose region (<0.3 dpa), while the formation of intermetallic second phase precipitation, resulting from transmutation, dominates the radiation-induced strengthening beginning with a relativelymore » modest dose (>0.6 dpa). Finally, the precipitate contribution is most pronounced for the HFIR irradiations, whereas the radiation-induced defect cluster microstructure can rationalize the entirety of the hardness increase observed in tungsten irradiated in the fast neutron spectrum of Joyo and the mixed neutron spectrum of JMTR.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1327659','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1327659"><span>Irradiation <span class="hlt">hardening</span> of pure tungsten exposed to neutron irradiation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Kumar, N. A. P. Kiran; Snead, Lance L.; Wirth, Brian D.; Katoh, Yutai</p> <p>2016-08-26</p> <p>In this paper, pure tungsten samples have been neutron irradiated in HFIR at 90–850 °C to 0.03–2.2 dpa. A dispersed barrier <span class="hlt">hardening</span> model informed by the available microstructure data has been used to predict the hardness. Comparison of the model predictions and the measured Vickers hardness reveals the dominant <span class="hlt">hardening</span> contribution at various irradiation conditions. For tungsten samples irradiated in HFIR, the results indicate that voids and dislocation loops contributed to the hardness increase in the low dose region (<0.3 dpa), while the formation of intermetallic second phase precipitation, resulting from transmutation, dominates the radiation-induced strengthening beginning with a relatively modest dose (>0.6 dpa). Finally, the precipitate contribution is most pronounced for the HFIR irradiations, whereas the radiation-induced defect cluster microstructure can rationalize the entirety of the hardness increase observed in tungsten irradiated in the fast neutron spectrum of Joyo and the mixed neutron spectrum of JMTR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..119a2006F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..119a2006F"><span>idRHa+ProMod - Rail <span class="hlt">Hardening</span> Control System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferro, L.</p> <p>2016-03-01</p> <p>idRHa+ProMod is the process control system developed by Primetals Technologies to foresee the thermo-mechanical evolution and micro-structural composition of rail steels subjected to slack quenching into idRHa+ Rail <span class="hlt">Hardening</span> equipments in a simulation environment. This tool can be used both off-line or in-line, giving the user the chance to test and study the best cooling strategies or letting the automatic control system free to adjust the proper cooling recipe. Optimization criteria have been tailored in order to determine the best cooling conditions according to the metallurgical requirements imposed by the main rail standards and also taking into account the elastoplastic bending phenomena occurring during all stages of the head <span class="hlt">hardening</span> process. The computational core of idRHa+ProMod is a thermal finite element procedure coupled with special algorithms developed to work out the main thermo-physical properties of steel, to predict the non-isothermal austenite decomposition into all the relevant phases and subsequently to evaluate the amount of latent heat of transformation released, the compound thermal expansion coefficient and the amount of plastic deformation in the material. Air mist and air blades boundary conditions have been carefully investigated by means of pilot plant tests aimed to study the jet impingement on rail surfaces and the cooling efficiency at all working conditions. Heat transfer coefficients have been further checked and adjusted directly on field during commissioning. idRHa+ is a trademark of Primetals Technologies Italy Srl</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008EOSTr..89..542G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008EOSTr..89..542G"><span>Widespread Secondary <span class="hlt">Volcanism</span> Near Northern Hawaiian Islands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garcia, Michael; Ito, Garrett; Weis, Dominique; Geist, Dennis; Swinnard, Lisa; Bianco, Todd; Flinders, Ashton; Taylor, Brian; Appelgate, Bruce; Blay, Chuck; Hanano, Diane; Nobre Silva, Inês; Naumann, Terry; Maerschalk, Claude; Harpp, Karen; Christensen, Branden; Sciaroni, Linda; Tagami, Taka; Yamasaki, Seiko</p> <p>2008-12-01</p> <p>Hot spot theory provides a key framework for understanding the motion of the tectonic plates, mantle convection and composition, and magma genesis. The age-progressive <span class="hlt">volcanism</span> that constructs many chains of islands throughout the world's ocean basins is essential to hot spot theory. In contrast, secondary <span class="hlt">volcanism</span>, which follows the main edifice-building stage of <span class="hlt">volcanism</span> in many chains including the Hawaii, Samoa, Canary, Mauritius, and Kerguelen islands, is not predicted by hot spot theory. Hawaiian secondary <span class="hlt">volcanism</span> occurs hundreds of kilometers away from, and more than 1 million years after, the end of the main shield <span class="hlt">volcanism</span>, which has generated more than 99% of the volume of the volcano's mass [Macdonald et al., 1983; Ozawa et al., 2005]. Diamond Head, in Honolulu, is the first and classic example of secondary <span class="hlt">volcanism</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014104','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014104"><span><span class="hlt">Volcanic</span> processes in the Solar System</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Carr, M.H.</p> <p>1987-01-01</p> <p>This article stresses that terrestrial <span class="hlt">volcanism</span> represents only part of the range of <span class="hlt">volcanism</span> in the solar system. Earth processes of <span class="hlt">volcanicity</span> are dominated by plate tectonics, which does not seem to operate on other planets, except possibly on Venus. Lunar <span class="hlt">volcanicity</span> is dominated by lava effusion at enormous rates. Mars is similar, with the addition to huge shield volcanoes developed over fixed hotspots. Io, the moon closest to Jupiter, is the most active body in the Solar System and, for example, much sulphur and silicates are emitted. The eruptions of Io are generated by heating caused by tides induced by Jupiter. Europa nearby seems to emit water from fractures and Ganymede is similar. The satellites of Saturn and Uranus are also marked by <span class="hlt">volcanic</span> craters, but they are of very low temperature melts, possibly of ammonia and water. The <span class="hlt">volcanism</span> of the solar system is generally more exotic, the greater the distance from Earth. -A.Scarth</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985JGR....9012901D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985JGR....9012901D"><span><span class="hlt">Volcanic</span> deposits in Antarctic snow and ice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Delmas, Robert J.; Legrand, Michel; Aristarain, Alberto J.; Zanolini, FrançOise</p> <p>1985-12-01</p> <p>Major <span class="hlt">volcanic</span> eruptions are able to spread large amounts of sulfuric acid all over the world. Acid layers of <span class="hlt">volcanic</span> origin were detected for the first time a few years ago by Hammer in Greenland ice. The present paper deals with <span class="hlt">volcanic</span> deposits in the Antarctic. The different methods that can be used to find <span class="hlt">volcanic</span> acid deposits in snow and ice cores are compared: electrical conductivity, sulfate, and acidity measurements. Numerous snow and ice samples collected at several Antarctic locations were analyzed. The results reveal that the two major <span class="hlt">volcanic</span> events recorded by H2SO4, fallout in Antarctic ice over the last century are the eruptions of Krakatoa (1883) and Agung (1963), both located at equatorial latitudes in the southern hemisphere. The <span class="hlt">volcanic</span> signals are found to be particularly well defined at central Antarctic locations apparently in relation to the low snow accumulation rates in these areas. It is demonstrated that <span class="hlt">volcanic</span> sulfuric acid in snow is not even partially neutralized by ammonia. The possible influence of Antarctic <span class="hlt">volcanic</span> activity on snow chemistry is also discussed, using the three recent eruptions of the Deception Island volcano as examples. Only one of them seems to have had a significant effect on the chemistry of snow at a location 200 km from this volcano. It is concluded that Antarctic <span class="hlt">volcanic</span> ice records are less complicated than Greenland records because of the limited number of volcanos in the southern hemisphere and the apparently higher signal to background ratio for acidity in Antarctica than in Greenland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70168931','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70168931"><span>The intensities and magnitudes of <span class="hlt">volcanic</span> eruptions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sigurdsson, H.</p> <p>1991-01-01</p> <p>Ever since 1935, when C.F Richter devised the earthquake magnitude scale that bears his name, seismologists have been able to view energy release from earthquakes in a systematic and quantitative manner. The benefits have been obvious in terms of assessing seismic gaps and the spatial and temporal trends of earthquake energy release. A similar quantitative treatment of <span class="hlt">volcanic</span> activity is of course equally desirable, both for gaining a further understanding of the physical principles of <span class="hlt">volcanic</span> eruptions and for <span class="hlt">volcanic</span>-hazard assessment. A systematic volcanologic data base would be of great value in evaluating such features as <span class="hlt">volcanic</span> gaps, and regional and temporal trends in energy release.  </p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MMTA...47.5280C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MMTA...47.5280C"><span>Continuous <span class="hlt">Hardening</span> During Isothermal Aging at 723 K (450 °C) of a Precipitation <span class="hlt">Hardening</span> Stainless Steel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Celada-Casero, Carola; Chao, Jesús; Urones-Garrote, Esteban; San Martin, David</p> <p>2016-11-01</p> <p>The isothermal aging behavior of a cold-rolled precipitation <span class="hlt">hardening</span> stainless steel has been studied at 723 K (450 °C) for holding times up to 72 hours. The precipitation <span class="hlt">hardening</span> has been investigated using microhardness Vickers (Hv), thermoelectric power (TEP) measurements, and tensile testing. Microhardness compared to TEP measurements is more sensitive to detect the initial stages of aging. Two precipitation regimes have been observed: the first one related to the formation of Cu-clusters for aging times below 1 hour and a second one associated with formation of Ni-rich precipitates. The results show that the material exhibits an outstanding continuous age strengthening response over the aging time investigated, reaching a hardness of 710 ± 4 HV1 and an ultimate tensile strength ( σ UTS) of 2.65 ± 0.02 GPa after 72 hours. Engineering stress-plastic strain curves reveal that the strength increases and the ductility decreases as the aging time increases. However, after prolonged holding times (24-72 hours) and, although small, a rise in both the strength and the total elongation is observed. The precipitation kinetics can be well predicted over the entire range of aging times by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Finally, a reliable linear hardness-yield strength correlation has been found, which enables a rapid evaluation of the strength from bulk hardness measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984JGR....89.8253K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984JGR....89.8253K"><span>Laboratory studies of <span class="hlt">volcanic</span> jets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kieffer, Susan Werner; Sturtevant, Bradford</p> <p>1984-09-01</p> <p>The study of the fluid dynamics of violent <span class="hlt">volcanic</span> eruptions by laboratory experiment is described, and the important fluid-dynamic processes that can be examined in laboratory models are discussed in detail. In preliminary experiments, pure gases are erupted from small reservoirs. The gases used are Freon 12 and Freon 22, two gases of high molecular weight and high density that are good analogs of heavy and particulate-laden <span class="hlt">volcanic</span> gases; nitrogen, a moderate molecular weight, moderate density gas for which the thermodynamic properties are well known; and helium, a low molecular weight, lowdensity gas that is used as a basis for comparison with the behavior of the heavier gases and as an analog of steam, the gas that dominates many <span class="hlt">volcanic</span> eruptions. Transient jets erupt from the reservoir into the laboratory upon rupture of a thin diaphragm at the exit of a convergent nozzle. The gas accelerates from rest in the reservoir to high velocity in the jet. Reservoir pressures and geometries are such that the fluid velocity in the jets is initially supersonic and later decays to subsonic. The measured reservoir pressure decreases as the fluid expands through repetitively reflecting rarefaction waves, but for the conditions of these experiments, a simple steady-discharge model is sufficient to explain the pressure decay and to predict the duration of the flow. Density variations in the flow field have been visualized with schlieren and shadowgraph photography. The observed structure of the jet is correlated with the measured pressure history. The starting vortex generated when the diaphragm ruptures becomes the head of the jet. Though the exit velocity is sonic, the flow head in the helium jet decelerates to about one-third of sonic velocity in the first few nozzle diameters, the nitrogen head decelerates to about three-fourths of sonic velocity, while Freon maintains nearly sonic velocity. The impulsive acceleration of reservoir fluid into the surrounding atmosphere</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.P42A..09J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P42A..09J"><span>Felsic <span class="hlt">Volcanics</span> on the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jolliff, B. L.; Lawrence, S. J.; Stopar, J.; Braden, S.; Hawke, B. R.; Robinson, M. S.; Glotch, T. D.; Greenhagen, B. T.; Seddio, S. M.</p> <p>2012-12-01</p> <p>Lunar Reconnaissance Orbiter (LRO) imaging and thermal data provide new morphologic and compositional evidence for features that appear to be expressions of nonmare silicic <span class="hlt">volcanism</span>. Examples reflecting a range of sizes and <span class="hlt">volcanic</span> styles include the Gruithuisen and Mairan Domes, and the Hansteen Alpha (H-A) and Compton-Belkovich (C-B) <span class="hlt">volcanic</span> complexes. In this work we combine new observations with existing compositional remote sensing and Apollo sample data to assess possible origins. Images and digital topographic data at 100 m scale (Wide Angle Camera) and ~0.5 to 2 m (Narrow Angle Camera) reveal (1) slopes on <span class="hlt">volcanic</span> constructs of ~12° to 27°, (2) potential endogenic summit depressions, (3) small domical features with dense boulder populations, and (4) irregular collapse features. Morphologies in plan view range from the circular to elliptical Gruithuisen γ and δ domes (~340 km2 each), to smaller cumulodomes such as Mairan T and C-B α (~30 km2, each), to the H-A (~375 km2) and C-B (~680 km2) <span class="hlt">volcanic</span> complexes. Heights range from ~800-1800 m, and most domes are relatively flat-topped or have a central depression. Positions of the Christiansen Feature in LRO Diviner data reflect silicic compositions [1]. Clementine UVVIS-derived FeO varies from ~5 to 10 wt%. Lunar Prospector Th data indicate model values of 20-55 ppm [2,3], which are consistent with compositions ranging from KREEP basalt to lunar granite. The Apollo collection contains small rocks and breccia clasts of felsic/granitic lithologies. Apollo 12 samples include small, pristine and brecciated granitic rock fragments and a large, polymict breccia (12013) consisting of felsic material (quartz & K-feldspar-rich) and mafic phases (similar to KREEP basalt). Many of the evolved lunar rocks have geochemically complementary compositions. The lithologic associations and the lack of samples with intermediate composition suggest a form of magmatic differentiation that produced mafic and felsic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780057800&hterms=Complex+Variables&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DComplex%2BVariables','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780057800&hterms=Complex+Variables&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DComplex%2BVariables"><span>The Procellarum <span class="hlt">volcanic</span> complexes - Contrasting styles of <span class="hlt">volcanism</span>. [lunar morphology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Whitford-Stark, J. L.; Head, J. W.</p> <p>1977-01-01</p> <p>Three major <span class="hlt">volcanic</span> complexes have long been recognized in the Oceanus Procellarum region. Detailed study shows that the complexes share some characteristics and also display major differences which provide clues to eruption style. The Rumker Hills occupy 5000 sq km in northern Procellarum and are apparently Imbrian-Eratosthenian in age; they are dominated by domes, suggesting relatively low effusion rates. The Aristarchus Plateau-Prinz/Harbinger region occupies 40,000 sq km in central Procellarum and is predominantly Imbrian in age; it is dominated by large sinuous rilles and associated dark mantling deposits of probable pyroclastic origin, suggesting relatively high eruption rates. The Marius Hills occupy 35,000 sq km in south-central Procellarum and appear to be predominantly Eratosthenian in age; they are dominated by low domes, steep domes, cones, and sinuous rilles, suggesting variable eruption rates and possible different volatile contents associated with eruption conditions that produced each type of feature. The <span class="hlt">volcanic</span> complexes, particularly Aristarchus and Marius, appear to be the sources for much of the central Procellarum mare fill.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JMEP...25.2727Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JMEP...25.2727Z"><span>The Effect of <span class="hlt">Hardenability</span> Variation on Phase Transformation of Spiral Bevel Gear in Quenching Process</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Yingtao; Shi, Wankai; Yang, Lin; Gu, Zhifei; Li, Zhichao</p> <p>2016-07-01</p> <p>The <span class="hlt">hardenability</span> of gear steel is dependent on the composition of alloying elements and is one of important criteria to assess process of phase transformation. The variation of <span class="hlt">hardenability</span> has to be considered in control of the microstructures and distortion during gear quenching. In this paper, the quantitative effect of <span class="hlt">hardenability</span> has been investigated on phase transformations of spiral bevel gears in die quenching. The <span class="hlt">hardenability</span> deviation of 22CrMoH steel was assessed by using Jominy test. The dilatometry experiments were conducted to build phase transformation kinetic models for steels with low and high <span class="hlt">hardenability</span>, respectively. The complete die quenching process of spiral bevel gear was modeled to reveal the significant difference on microstructures and temperature history with variation of <span class="hlt">hardenability</span>. The final microstructures of the gear are martensite in surface layer after quenching process. There are bainite inside the gear tooth and the mixture of bainite and ferrite inside gear for the gear with low <span class="hlt">hardenability</span>. The microstructure is bainite inside the gear with high <span class="hlt">hardenability</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830027108','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830027108"><span>Some new results on irradiation characteristics of synthetic quartz crystals and their application to radiation <span class="hlt">hardening</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bahadur, H.; Parshad, R.</p> <p>1983-01-01</p> <p>The paper reports some new results on irradiation characteristics of synthetic quartz crystals and their application to radiation <span class="hlt">hardening</span>. The present results show how the frequency shift in quartz crystals can be influenced by heat processing prior to irradiation and how this procedure can lead to radiation <span class="hlt">hardening</span> for obtaining precise frequencies and time intervals from quartz oscillators in space.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25214383','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25214383"><span>The effects of x-ray beam <span class="hlt">hardening</span> on detective quantum efficiency and radiation dose.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wong, Molly Donovan; Wu, Xizeng; Liu, Hong</p> <p>2011-01-01</p> <p>The goal of this preliminary study was to investigate the effects of x-ray beam <span class="hlt">hardening</span> on the detective quantum efficiency (DQE) and the radiation dose of an inline x-ray imaging system. The ability to decrease the risk of harmful radiation to the patient without compromising the detection capability would more effectively balance the tradeoff between image quality and radiation dose, and therefore benefit the fields of diagnostic x-ray imaging, especially mammography. The DQE and the average glandular dose were both calculated under the same experimental conditions for a range of beam <span class="hlt">hardening</span> levels, corresponding to no added beam <span class="hlt">hardening</span> and two thicknesses each of Rhodium (Rh) and Molybdenum (Mo) filters. The dose calculation results demonstrate a reduction of 15% to 24% for the range of beam <span class="hlt">hardening</span> levels. The comparison of all quantities comprising the DQE exhibit very close correlation between the results obtained without added beam <span class="hlt">hardening</span> to the results corresponding to the range of beam <span class="hlt">hardening</span> levels. For the specific experimental conditions utilized in this preliminary study, the results are an indication that the use of beam <span class="hlt">hardening</span> holds the potential to reduce the radiation dose without decreasing the performance of the system. Future studies will seek to apply this method in a clinical environment and perform a comprehensive image quality evaluation, in an effort to further evaluate the potential of beam <span class="hlt">hardening</span> to balance the tradeoff between dose and image quality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26701056','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26701056"><span>Thermal vesiculation during <span class="hlt">volcanic</span> eruptions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lavallée, Yan; Dingwell, Donald B; Johnson, Jeffrey B; Cimarelli, Corrado; Hornby, Adrian J; Kendrick, Jackie E; von Aulock, Felix W; Kennedy, Ben M; Andrews, Benjamin J; Wadsworth, Fabian B; Rhodes, Emma; Chigna, Gustavo</p> <p>2015-12-24</p> <p>Terrestrial <span class="hlt">volcanic</span> eruptions are the consequence of magmas ascending to the surface of the Earth. This ascent is driven by buoyancy forces, which are enhanced by bubble nucleation and growth (vesiculation) that reduce the density of magma. The development of vesicularity also greatly reduces the 'strength' of magma, a material parameter controlling fragmentation and thus the explosive potential of the liquid rock. The development of vesicularity in magmas has until now been viewed (both thermodynamically and kinetically) in terms of the pressure dependence of the solubility of water in the magma, and its role in driving gas saturation, exsolution and expansion during decompression. In contrast, the possible effects of the well documented negative temperature dependence of solubility of water in magma has largely been ignored. Recently, petrological constraints have demonstrated that considerable heating of magma may indeed be a common result of the latent heat of crystallization as well as viscous and frictional heating in areas of strain localization. Here we present field and experimental observations of magma vesiculation and fragmentation resulting from heating (rather than decompression). Textural analysis of <span class="hlt">volcanic</span> ash from Santiaguito volcano in Guatemala reveals the presence of chemically heterogeneous filaments hosting micrometre-scale vesicles. The textures mirror those developed by disequilibrium melting induced via rapid heating during fault friction experiments, demonstrating that friction can generate sufficient heat to induce melting and vesiculation of hydrated silicic magma. Consideration of the experimentally determined temperature and pressure dependence of water solubility in magma reveals that, for many ascent paths, exsolution may be more efficiently achieved by heating than by decompression. We conclude that the thermal path experienced by magma during ascent strongly controls degassing, vesiculation, magma strength and the effusive</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....13322W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....13322W"><span>Isotopic heterogeneity in <span class="hlt">volcanic</span> rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wolff, J. A.; Ramos, F. C.; Tollstrup, D. L.</p> <p>2003-04-01</p> <p>The growing microsample database on <span class="hlt">volcanic</span> rocks is showing that isotopic disequilibrium between and among phenocryst phases, their melt inclusions, and groundmass is the rule rather than the exception. This applies even in cases of little or no petrographic evidence for disequilibrium. Erupted magmas must therefore be regarded, to some extent, as mechanical mixtures of isotopically distinct components assembled from different sources. The preservation of isotopic disequilibrium requires that the assembly takes place before diffusion can eradicate evidence of disequilibrium. For a wide range of magmas (mafic, intermediate and felsic, silica under- and oversaturated) from different volcano types (flood basalts, monogenetic cones, stratocones, silicic calderas) this timescale ranges from thousands of years down to one year or less, with no consistent pattern of mixing-to-eruption time vs. volcano or magma type. Among many issues arising from these findings, we note that estimation of magmatic temperatures from application of equilibrium thermodynamics to phenocryst assemblages in <span class="hlt">volcanic</span> rocks should be approached with extreme caution. The isotope ratio variations observed among the components of a single <span class="hlt">volcanic</span> rock sample, in most cases, indicate interaction between magma and the local wall-rock. This is consistent with the view that the vast majority of magmas undergo modification during transport through and residence within the crust. Three physical origins of heterogeneity have been proposed: melting of wallrock, magmatic recharge, and mixing of components within a magma chamber initially segregated into melt-rich and crystal-rich portions. Time constraints on preservation of disequilibrium imply either a causal link with eruption, or that these processes occur through the lifetime of a chamber.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Natur.528..544L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Natur.528..544L"><span>Thermal vesiculation during <span class="hlt">volcanic</span> eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lavallée, Yan; Dingwell, Donald B.; Johnson, Jeffrey B.; Cimarelli, Corrado; Hornby, Adrian J.; Kendrick, Jackie E.; von Aulock, Felix W.; Kennedy, Ben M.; Andrews, Benjamin J.; Wadsworth, Fabian B.; Rhodes, Emma; Chigna, Gustavo</p> <p>2015-12-01</p> <p>Terrestrial <span class="hlt">volcanic</span> eruptions are the consequence of magmas ascending to the surface of the Earth. This ascent is driven by buoyancy forces, which are enhanced by bubble nucleation and growth (vesiculation) that reduce the density of magma. The development of vesicularity also greatly reduces the ‘strength’ of magma, a material parameter controlling fragmentation and thus the explosive potential of the liquid rock. The development of vesicularity in magmas has until now been viewed (both thermodynamically and kinetically) in terms of the pressure dependence of the solubility of water in the magma, and its role in driving gas saturation, exsolution and expansion during decompression. In contrast, the possible effects of the well documented negative temperature dependence of solubility of water in magma has largely been ignored. Recently, petrological constraints have demonstrated that considerable heating of magma may indeed be a common result of the latent heat of crystallization as well as viscous and frictional heating in areas of strain localization. Here we present field and experimental observations of magma vesiculation and fragmentation resulting from heating (rather than decompression). Textural analysis of <span class="hlt">volcanic</span> ash from Santiaguito volcano in Guatemala reveals the presence of chemically heterogeneous filaments hosting micrometre-scale vesicles. The textures mirror those developed by disequilibrium melting induced via rapid heating during fault friction experiments, demonstrating that friction can generate sufficient heat to induce melting and vesiculation of hydrated silicic magma. Consideration of the experimentally determined temperature and pressure dependence of water solubility in magma reveals that, for many ascent paths, exsolution may be more efficiently achieved by heating than by decompression. We conclude that the thermal path experienced by magma during ascent strongly controls degassing, vesiculation, magma strength and the effusive</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930022764&hterms=Loess&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DLoess','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930022764&hterms=Loess&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DLoess"><span>Chemical transport during formation and alteration of Martian impact and <span class="hlt">volcanic</span> deposits</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Newsom, H. E.</p> <p>1992-01-01</p> <p>Much of the surface of Mars, including <span class="hlt">volcanic</span> and cratered terrains, probably experienced alteration and degassing processes. These processes may have depleted or enriched many important elements in surface materials, including bedrock, dust, and <span class="hlt">soils</span>. The composition of the martian <span class="hlt">soil</span> may represent the best estimate, for some elements, of the average composition of the martian crust, similar to the composition of loess created by glacial action on the Earth. The martian <span class="hlt">soil</span> may represent the only convenient, globally or regionally averaged sample of the martian crust. In order to understand the composition of the source material for the <span class="hlt">soil</span>, however, we need to understand the contributions of <span class="hlt">volcanic</span> vs. impact sources for this material and the chemical fractionations involved in its production. The processes to be addressed include degassing of <span class="hlt">volcanic</span> deposits, as observed in the Valley of Ten Thousand Smokes at Katmai, Alaska, and degassing of meltbearing impact ejecta as inferred for suevite ejecta sheets at the Ries Crater, and alteration or palagonitization of <span class="hlt">volcanic</span> deposits, as documented for volcanos in British Columbia and many other <span class="hlt">volcanic</span> terrains, and impact crater deposits. The process of palagonitization has been the subject of several studies with reference to Mars, and palagonite is a good analogue for the spectroscopic properties of the martian dust. The role of impact in cratering has not been as well studied, although other researchers have established that both degassing and alteration are common features of impact crater deposits. Other relevant sources of experimental data include the extensive literature on the corrosion of nuclear waste glass and leaching of shocked materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.191..216S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.191..216S"><span>Water in <span class="hlt">volcanic</span> glass: From <span class="hlt">volcanic</span> degassing to secondary hydration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seligman, Angela N.; Bindeman, Ilya N.; Watkins, James M.; Ross, Abigail M.</p> <p>2016-10-01</p> <p><span class="hlt">Volcanic</span> glass is deposited with trace amounts (0.1-0.6 wt.%) of undegassed magmatic water dissolved in the glass. After deposition, meteoric water penetrates into the glass structure mostly as molecular H2O. Due to the lower δD (‰) values of non-tropical meteoric waters and the ∼30‰ offset between <span class="hlt">volcanic</span> glass and environmental water during hydration, secondary water imparts lighter hydrogen isotopic values during secondary hydration up to a saturation concentration of 3-4 wt.% H2O. We analyzed compositionally and globally diverse <span class="hlt">volcanic</span> glass from 0 to 10 ka for their δD and H2Ot across different climatic zones, and thus different δD of precipitation, on a thermal conversion elemental analyzer (TCEA) furnace attached to a mass spectrometer. We find that tephrachronologically coeval rhyolite glass is hydrated faster than basaltic glass, and in the majority of glasses an increase in age and total water content leads to a decrease in δD (‰), while a few equatorial glasses have little change in δD (‰). We compute a magmatic water correction based on our non-hydrated glasses, and calculate an average 103lnαglass-water for our hydrated felsic glasses of -33‰, which is similar to the 103lnαglass-water determined by Friedman et al. (1993a) of -34‰. We also determine a smaller average 103lnαglass-water for all our mafic glasses of -23‰. We compare the δD values of water extracted from our glasses to local meteoric waters following the inclusion of a -33‰ 103lnαglass-water. We find that, following a correction for residual magmatic water based on an average δD and wt.% H2Ot of recently erupted ashes from our study, the δD value of water extracted from hydrated <span class="hlt">volcanic</span> glass is, on average, within 4‰ of local meteoric water. To better understand the difference in hydration rates of mafic and felsic glasses, we imaged 6 tephra clasts ranging in age and chemical composition with BSE (by FEI SEM) down to a submicron resolution. Mafic tephra</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/tem/1089/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/tem/1089/report.pdf"><span>Sub-glacial <span class="hlt">volcanic</span> eruptions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>White, Donald Edward</p> <p>1956-01-01</p> <p>The literature on sub-glacial <span class="hlt">volcanic</span> eruptions and the related flood phenomena has been reviewed as a minor part of the larger problem of convective and conductive heat transfer from intrusive magma. (See Lovering, 1955, for a review of the extensive literature on this subject.) This summary of data on sub-glacial eruptions is part of a program that the U.S. Geological Survey is conducting in connection with its Investigations of Geologic Processes project on behalf of the Division of Research, U.S. Atomic Energy Commission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhDT.......174P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhDT.......174P"><span>Experimental study of self-compacted concrete in <span class="hlt">hardened</span> state</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parra Costa, Carlos Jose</p> <p></p> <p>The main aim of this work is to investigate the <span class="hlt">hardened</span> behaviour of Self-Compacting Concrete (SCC). Self compacting Concrete is a special concrete that can flow in its gravity and fill in the formwork alone to its self-weight, passing through the bars and congested sections without the need of any internal or external vibration, while maintaining adequate homogeneity. SCC avoids most of the materials defects due to bleeding or segregation. With regard to its composition, SCC consists of the same components as traditional vibrated concrete (TC), but in different proportions. Thus, the high amount of superplasticizer and high powder content have to taken into account. The high workability of SCC does not allow to use traditional methods for measuring the fresh state properties, so new tests has developed (slump-flow, V-funnel, L-box, and others). The properties of the <span class="hlt">hardened</span> SCC, which depend on the mix design, should be different from traditional concrete. In order to study the possible modifications of SCC <span class="hlt">hardened</span> state properties, a review of the bibliography was done. The state of art was focused on the mechanical behaviour (compressive strength, tension strength and elastic modulus), on bond strength of reinforcement steel, and on material durability. The experimental program consisted in the production of two types of concretes: Self-Compacting Concrete and Traditional Concrete. Four different dosages was made with three different water/cement ratio and two strength types of Portland cement, in order to cover the ordinary strength used in construction. Based on this study it can be concluded that compressive strength of SCC and TC are similar (the differences are lesser than 10%), whereas the tensile strength of TC are up to 18% higher. The values of elastic modulus of both concrete are similar. On the other hand, in the ultimate state the bond strength of SCC and TC is similar, although SCC shows higher bond stiffness in the serviceability state (initial</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PMB....62.1810L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PMB....62.1810L"><span>A fast beam <span class="hlt">hardening</span> correction method incorporated in a filtered back-projection based MAP algorithm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luo, Shouhua; Wu, Huazhen; Sun, Yi; Li, Jing; Li, Guang; Gu, Ning</p> <p>2017-03-01</p> <p>The beam <span class="hlt">hardening</span> effect can induce strong artifacts in CT images, which result in severely deteriorated image quality with incorrect intensities (CT numbers). This paper develops an effective and efficient beam <span class="hlt">hardening</span> correction algorithm incorporated in a filtered back-projection based maximum a posteriori (BHC-FMAP). In the proposed algorithm, the beam <span class="hlt">hardening</span> effect is modeled and incorporated into the forward-projection of the MAP to suppress beam <span class="hlt">hardening</span> induced artifacts, and the image update process is performed by Feldkamp–Davis–Kress method based back-projection to speed up the convergence. The proposed BHC-FMAP approach does not require information about the beam spectrum or the material properties, or any additional segmentation operation. The proposed method was qualitatively and quantitatively evaluated using both phantom and animal projection data. The experimental results demonstrate that the BHC-FMAP method can efficiently provide a good correction of beam <span class="hlt">hardening</span> induced artefacts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28052045','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28052045"><span>A fast beam <span class="hlt">hardening</span> correction method incorporated in a filtered back-projection based MAP algorithm.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Luo, Shouhua; Wu, Huazhen; Sun, Yi; Li, Jing; Li, Guang; Gu, Ning</p> <p>2017-03-07</p> <p>The beam <span class="hlt">hardening</span> effect can induce strong artifacts in CT images, which result in severely deteriorated image quality with incorrect intensities (CT numbers). This paper develops an effective and efficient beam <span class="hlt">hardening</span> correction algorithm incorporated in a filtered back-projection based maximum a posteriori (BHC-FMAP). In the proposed algorithm, the beam <span class="hlt">hardening</span> effect is modeled and incorporated into the forward-projection of the MAP to suppress beam <span class="hlt">hardening</span> induced artifacts, and the image update process is performed by Feldkamp-Davis-Kress method based back-projection to speed up the convergence. The proposed BHC-FMAP approach does not require information about the beam spectrum or the material properties, or any additional segmentation operation. The proposed method was qualitatively and quantitatively evaluated using both phantom and animal projection data. The experimental results demonstrate that the BHC-FMAP method can efficiently provide a good correction of beam <span class="hlt">hardening</span> induced artefacts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21516721','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21516721"><span>New distortional <span class="hlt">hardening</span> model capable of predicting eight ears for textured aluminum sheet</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yoon, J. H.; Cazacu, O.; Yoon, J. W.; Dick, R. E.</p> <p>2011-05-04</p> <p>The effects of the anisotropy evolution and of the directionality in <span class="hlt">hardening</span> on the predictions of the earing profile of a strongly textured aluminum alloy are investigated using a new distortional <span class="hlt">hardening</span> model that incorporates multiple <span class="hlt">hardening</span> curves corresponding to uniaxial tension along several orientations with respect to the rolling direction, and to biaxial tension. Yielding is described using a form of CPB06ex2 yield function (Plunkett et al. (2008)) which is tailored for metals with no tension-compression asymmetry. It is shown that even if directional <span class="hlt">hardening</span> and its evolution are neglected, this yield function predicts a cup with eight ears as was observed experimentally. However, directional <span class="hlt">hardening</span> can be of considerable importance for improved accuracy in prediction of the non-uniformity of the cup height profile.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813878L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813878L"><span>Automatic semi-continuous accumulation chamber for diffuse gas emissions monitoring in <span class="hlt">volcanic</span> and non-<span class="hlt">volcanic</span> areas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lelli, Matteo; Raco, Brunella; Norelli, Francesco; Virgili, Giorgio; Continanza, Davide</p> <p>2016-04-01</p> <p>Since various decades the accumulation chamber method is intensively used in monitoring activities of diffuse gas emissions in <span class="hlt">volcanic</span> areas. Although some improvements have been performed in terms of sensitivity and reproducibility of the detectors, the equipment used for measurement of gas emissions temporal variation usually requires expensive and bulky equipment. The unit described in this work is a low cost, easy to install-and-manage instrument that will make possible the creation of low-cost monitoring networks. The Non-Dispersive Infrared detector used has a concentration range of 0-5% CO2, but the substitution with other detector (range 0-5000 ppm) is possible and very easy. Power supply unit has a 12V, 7Ah battery, which is recharged by a 35W solar panel (equipped with charge regulator). The control unit contains a custom programmed CPU and the remote transmission is assured by a GPRS modem. The chamber is activated by DataLogger unit, using a linear actuator between the closed position (sampling) and closed position (idle). A probe for the measure of <span class="hlt">soil</span> temperature, <span class="hlt">soil</span> electrical conductivity, <span class="hlt">soil</span> volumetric water content, air pressure and air temperature is assembled on the device, which is already arranged for the connection of others external sensors, including an automatic weather station. The automatic station has been tested on the field at Lipari island (Sicily, Italy) during a period of three months, performing CO2 flux measurement (and also weather parameters), each 1 hour. The possibility to measure in semi-continuous mode, and at the same time, the gas fluxes from <span class="hlt">soil</span> and many external parameters, helps the time series analysis aimed to the identification of gas flux anomalies due to variations in deep system (e.g. onset of <span class="hlt">volcanic</span> crises) from those triggered by external conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AdG....22..125T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AdG....22..125T"><span><span class="hlt">Volcanism</span> and associated hazards: the Andean perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tilling, R. I.</p> <p>2009-12-01</p> <p>Andean <span class="hlt">volcanism</span> occurs within the Andean <span class="hlt">Volcanic</span> Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin <span class="hlt">volcanic</span> arc, which consists of four distinct segments: Northern <span class="hlt">Volcanic</span> Zone, Central <span class="hlt">Volcanic</span> Zone, Southern <span class="hlt">Volcanic</span> Zone, and Austral <span class="hlt">Volcanic</span> Zone. These segments are separated by <span class="hlt">volcanically</span> inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain <span class="hlt">volcanism</span>. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other <span class="hlt">volcanic</span> region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (<0.05 km3) in 1985 of Nevado del Ruiz (Colombia) killed about 25 000 people - the worst <span class="hlt">volcanic</span> disaster in the Andean region as well as the second worst in the world in the 20th century. The Ruiz tragedy has been attributed largely to ineffective communications of hazards information and indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia, Ecuador, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70033968','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70033968"><span><span class="hlt">Volcanism</span> and associated hazards: The Andean perspective</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Tilling, R.I.</p> <p>2009-01-01</p> <p>Andean <span class="hlt">volcanism</span> occurs within the Andean <span class="hlt">Volcanic</span> Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin <span class="hlt">volcanic</span> arc, which consists of four distinct segments: Northern <span class="hlt">Volcanic</span> Zone, Central <span class="hlt">Volcanic</span> Zone, Southern <span class="hlt">Volcanic</span> Zone, and Austral <span class="hlt">Volcanic</span> Zone. These segments are separated by <span class="hlt">volcanically</span> inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain <span class="hlt">volcanism</span>. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other <span class="hlt">volcanic</span> region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. <br><br> The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (<0.05 km 3) in 1985 of Nevado del Ruiz (Colombia) killed about 25 000 people - the worst <span class="hlt">volcanic</span> disaster in the Andean region as well as the second worst in the world in the 20th century. The Ruiz tragedy has been attributed largely to ineffective communications of hazards information and indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MMTA...46..456L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MMTA...46..456L"><span>Development of a Press-<span class="hlt">Hardened</span> Steel Suitable for Thin Slab Direct Rolling Processing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Jewoong; De Cooman, Bruno C.</p> <p>2015-01-01</p> <p>The thin slab casting and direct rolling process is a hot-rolled strip production method which has maintained commercial quality steel grades as a major material in many industrial applications due to its low processing cost. Few innovative products have however been developed specifically for production by thin slab direct rolling. Press <span class="hlt">hardening</span> or hot press forming steel grades which are now widely used to produce structural automotive steel parts requiring ultra-high strength and formability may however offer an opportunity for thin slab direct rolling-specific ultra-high strength products. In this work, a newly designed press <span class="hlt">hardening</span> steel grade developed specifically for thin slab direct rolling processing is presented. The press <span class="hlt">hardening</span> steel has a high nitrogen content compared with press <span class="hlt">hardening</span> steel grades produced by conventional steelmaking routes. Boron and titanium which are key alloying additions in conventional press <span class="hlt">hardening</span> steel such as the 22MnB5 press <span class="hlt">hardening</span> steel grade are not utilized. Cr is added in the press <span class="hlt">hardening</span> steel to obtain the required <span class="hlt">hardenability</span>. The properties of the new thin slab direct rolling-specific 22MnCrN5 press <span class="hlt">hardening</span> steel grade are reviewed. The evolution of the microstructure and mechanical properties with increasing amounts of Cr additions from 0.6 to 1.4 wt pct and the effect of the cooling rate during die-quenching were studied by means of laboratory simulations. The selection of the optimum chemical composition range for the thin slab direct rolling-specific 22MnCrN5 steel in press <span class="hlt">hardening</span> heat treatment conditions is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUSM.V23B..05P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUSM.V23B..05P"><span>The Global Water Cycle Drives <span class="hlt">Volcanism</span> on Seasonal to Millennial Timescales</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pyle, D. M.; Mason, B. G.; Jupp, T. E.; Dade, W. B.</p> <p>2005-05-01</p> <p>Global rates of occurrence of <span class="hlt">volcanic</span> eruptions show periodic behaviour on timescales ranging from <1 yr (seasonal) to >106 years. At long timescales (>106 to 107 years), rates of eruption are controlled by plate tectonics. At shorter timescales, the periodic nature of <span class="hlt">volcanism</span> is forced by the global water cycle. Historical records of the rates of onset of eruption for the past 300 years are dominated by small-scale activity at a number of persistently, or repeatedly, active volcanoes around the world. This record shows statistically significant evidence for `seasonality': globally, rates of eruption are about 18% higher during northern hemisphere winter than northern hemisphere summer. This pattern of seasonality is strong for volcanoes at high northern latitudes; but also exists for <span class="hlt">volcanic</span> regions in the southern hemisphere (e.g. Chile) and at specific volcanoes (e.g. Sakurajima, Japan). Seasonality is weak at certain ocean-island volcanoes (e.g. Hawaii), and certain <span class="hlt">volcanic</span> regions (e.g. Mediterranean). The only external parameters that account for the periodic nature of small-scale <span class="hlt">volcanism</span> (i.e. the observation that eruption rates peak between November and March in both hemispheres) are those related to the global water cycle. Movement of water (including atmospheric vapour; <span class="hlt">soil</span> moisture; snow and ice) between the northern-hemisphere continents and the world's oceans is responsible for an annual deformation of Earth's surface that is weakly defined in equatorial regions, and stronger at higher latitudes. This external modulation of the Earth's surface has an amplitude of the order of centimetres, and an associated (vertical) strain rate of ~ 10-16 s-1. This deformation is slow enough to be felt by the Earth's interior, and is of the same order of magnitude as the (horizontal) strain rates experienced in tectonically active continental regions. This modulation effectively applies a time-dependence to the `threshold' point at which a volcano will begin</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1214616S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1214616S"><span>GOSAT/TANSO-FTS Measurement of <span class="hlt">Volcanic</span> and Geothermal CO2 Emissions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schwandner, Florian M.; Carn, Simon A.; Newhall, Christopher G.</p> <p>2010-05-01</p> <p>Approximately one tenth of the Earth's human population lives in direct reach of <span class="hlt">volcanic</span> hazards. Being able to provide sufficiently early and scientifically sound warning is a key to <span class="hlt">volcanic</span> hazard mitigation. Quantitative time-series monitoring of <span class="hlt">volcanic</span> CO2 emissions will likely play a key role in such early warning activities in the future. Impending <span class="hlt">volcanic</span> eruptions or any potentially disastrous activity that involves movement of magma in the subsurface, is often preceded by an early increase of CO2 emissions. Conventionally, <span class="hlt">volcanic</span> CO2 monitoring is done either in campaigns of <span class="hlt">soil</span> emission measurements (grid of one-time measuring points) that are labor intensive and slow, or by ground-based remote FTIR measurements in emission plumes. These methods are not easily available at all sites of potential activity and prohibitively costly to employ on a large number of volcanoes. In addition, both of these ground-based approaches pose a significant risk to the workers conducting these measurements. Some aircraft-based measurements have been conducted as well in the past, however these are limited by the usually meager funding situation of individual observatories, the hazard such flights pose to equipment and crew, and by the inaccessibility of parts of the plume due to ash hazards. The core motivation for this study is therefore to develop a method for <span class="hlt">volcanic</span> CO2 monitoring from space that will provide sufficient coverage, resolution, and data quality for an application to quantitative time series monitoring and correlation with other available datasets, from a safe distance and with potentially global reach. In summary, the purpose of the proposed research is to quantify <span class="hlt">volcanic</span> CO2 emissions using satellite-borne observations. Quantitative estimates will be useful for warning of impending <span class="hlt">volcanic</span> eruptions, and assessing the contribution of <span class="hlt">volcanic</span> CO2 to global GHG. Our approach encompasses method development and testing for the detection of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26094470','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26094470"><span>[Sediment transport characteristics at different erosion stages for non-<span class="hlt">hardened</span> roads of the Shenfu Coalfield, west China].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guo, Ming-ming; Wang, Wen-long; Li, Jian-ming; Huang, Peng-fei; Zhu, Bao-cai; Wang, Zhen; Luo, Ting</p> <p>2015-02-01</p> <p>Non-<span class="hlt">hardened</span> roads formed in the production of the Shenfu Coalfield have a unique condition of underlying surface. The road surface is composed of a regolith layer with a certain thickness resulted from long-term rolling and thus, is characterized by weakened anti-scourabilty and anti-erodibility. In contrast, <span class="hlt">soil</span> layer below the regolith has a higher bulk density and anti-erodibility. The processes of <span class="hlt">soil</span> erosion on the non-<span class="hlt">hardened</span> roads exhibit some differences under rainfall condition. The process of sediment transport and the relationship between sediment transport rate and erosion factors at different erosion stages were studied on non-<span class="hlt">hardened</span> roads with slope degrees ranging from 3° to 12° (3°, 6°, 9°, 12°) by a field experiment under artificial rainfall. Results showed that the first peak of sediment transport on the regolith surface was observed at the sheet erosion stage. Sheet erosion occurred only at 3° slope degree, with an average variation coefficient of 0.07 for sediment transport rate. Rills in every testing began to develop at slope degrees of 6° to 12° about 15 min after runoff initiation. At the sheet erosion stage, the process of sediment transport fluctuated considerably at rainfall intensities of > 1.5 mm · min(-1), but the differences in its variation were little at the three slope degrees, with average variation coefficients of 0.20, 0.19 and 0.16, respectively. Rainfall intensity had a more significant impact on sediment transport rate than slope degree. The process of sediment transport at the rill erosion stage fluctuated, but the fluctuation was obviously smaller than that at the sheet erosion stage, with average variation coefficients of 0.05, 0.09 and 0.10 at the three slope degrees. Many wide and shallow rills evolved at the rill erosion stage. The sediment transport rate could be well predicted by a power function of rainfall intensity and slope degree at the sheet and rill erosion stages. The stable sediment transport</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70162570','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70162570"><span><span class="hlt">Volcanic</span> eruptions; energy and size</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>de la Cruz-Reyna, S.</p> <p>1991-01-01</p> <p>The Earth is a dynamic planet. Many different processes are continuously developing, creating a delicate balance between the energy stored and generated in its interior and the heat lost into space. The heat in continuously transferred through complex self-regulating convection mechanisms on a planetary scale. The distribution of terrestrial heat flow reveals some of the fine structure of the energy transport mechanisms in the outer layers of the Earth. Of these mechanisms in the outer layers of the Earth. Of these mechanisms, <span class="hlt">volcanism</span> is indeed the most remarkable, for it allows energy to be transported in rapid bursts to the surface. In order to maintain the subtle balance of the terrestrial heat machine, one may expect that some law or principle restricts the ways in which these <span class="hlt">volcanic</span> bursts affect the overall energy transfer of the Earth. For instance, we know that the geothermal flux of the planet amounts to 1028 erg/year. On the other hand, a single large event like the Lava Creek Tuff eruption that formed Yellowstone caldera over half a million years ago may release the same amount of energy in a very small area, over a short period of time. </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.5856B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.5856B"><span>Bromine oxidation in <span class="hlt">volcanic</span> plumes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bobrowski, N.; Vogel, L.; Kern, C.; Giuffrida, G. B.; Delgado-Granados, H.; Platt, U.</p> <p>2009-04-01</p> <p>Volcanoes are very strong sources of hydrogen, carbon, sulphur and halogen compounds, as well as of particles. Some gases only behave as passive tracers; others interact and affect the formation, growth or chemical characteristics of aerosol particles in a complex system. Recent measurements of halogen radicals in <span class="hlt">volcanic</span> plumes showed that <span class="hlt">volcanic</span> plumes are chemically very active. Kinetic considerations (Oppenheimer et al., 2006) and detailed calculations with an atmospheric chemistry model (Bobrowski et al., 2007) explain the halogen chemistry mainly with photochemical reactions involving both, the gas and particle phase. They reproduce the measured gas-phase concentrations quite well. However, temporal evolution of BrO in the early plume is not well described in the models. The understanding of chemical kinetics of BrO formation is still not complete. Recent measurement results (Vogel et al., 2008) do not fit with initial model calculation. The new data lead to the suggestion that the BrO formation could be much faster during the first few minutes after emission than initially suggested. Old and recent data sets will be confronted, compared and possible causes of their differences discussed. The measurements considered were taken at Mt. Etna (Italy), Villarica (Chile), and Popocatépetl (Mexico) volcanoes. Additionally, at Mt Etna the emission consists of up to four individual plumes from four summit craters. The differences between the individual plumes have been investigated during the last years and will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMAE31A..01T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMAE31A..01T"><span>Observations of <span class="hlt">volcanic</span> Lightning (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomas, R. J.; Behnke, S. A.; Krehbiel, P. R.; Rison, W.; Edens, H. E.; McNutt, S. R.</p> <p>2010-12-01</p> <p>We have made detailed observations of lightning during four <span class="hlt">volcanic</span> eruptions using lightning mapping array (LMA) stations. In January 2006 we observed several explosive eruptions from Augustine Volcano in Alaska with two LMA stations. While two stations only gave us the direction to the lightning it gave a detailed time history of the lightning in relationship to the eruption as measured by seismic and acoustic instruments. We inferred that there were two phases (explosive and plume) and three types of lightning (small discharges near the vent, larger discharges in the <span class="hlt">volcanic</span> column, thunderstorm like lightning in the plume). In May 2008 we mapped lightning in the plume of Chaitan (Chile) three weeks after the initial eruption. In 2009 we observed the entire sequence of explosive eruptions of Redoubt Volcano in Alaska with 4 distant stations. This provided good 2-D locations of the electrical activity. In 2010 we mapped much of the eruption of Eyjafjallajökull using 6 LMA stations that provided 3-D locations. All the observations have reinforced the basic conclusions that we found at the Augustine eruption, and let us expand and refine the these ideas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/863236','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/863236"><span>Gamma prime <span class="hlt">hardened</span> nickel-iron based superalloy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Korenko, Michael K.</p> <p>1978-01-01</p> <p>A low swelling, gamma prime <span class="hlt">hardened</span> nickel-iron base superalloy useful for fast reactor duct and cladding applications is described having from about 7.0 to about 10.5 weight percent (wt%) chromium, from about 24 to about 35 wt% nickel, from about 1.7 to about 2.5 wt% titanium, from about 0.3 to about 1.0 wt% aluminum, from about 2.0 to about 3.3 wt% molybdenum, from about 0.05 to about 1.0 wt% silicon, from about 0.03 to about 0.06 wt% carbon, a maximum of about 2 wt% manganese, and the balance iron.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000ApPhL..76.3786G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000ApPhL..76.3786G"><span>Pr-Zr-Co precipitation-<span class="hlt">hardened</span> magnet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gabay, A. M.; Zhang, Yong; Hadjipanayis, G. C.</p> <p>2000-06-01</p> <p>Hard magnetic properties have been found in homogenized and subsequently aged Pr-Zr-Co alloys. Transmission electron microscopy reveals a microstructure consisting of a Pr2(Co, Zr)17 matrix with (Pr, Zr)Co5 precipitates formed after aging the homogenized alloys with the (Pr, Zr)Co5+δ structure. This microstructure is similar to that of the Sm-Co-Cu-Zr precipitation-<span class="hlt">hardened</span> magnets. However, unlike Sm2Co17, the easy magnetization direction (EMD) of Pr2Co17 lies in a basal plane. The coexistence of the 2:17 matrix phase with EMD∥(001) and the 1:5 cell-boundary phase with EMD∥[001] results in unusual alignment effects. Anisotropic Pr11.5Zr4Co85 powders with coercivity of 4.1 kOe and energy product of 7.2 MGOe were obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21476603','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21476603"><span>Topographies of plasma-<span class="hlt">hardened</span> surfaces of poly(dimethylsiloxane)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goerrn, Patrick; Wagner, Sigurd</p> <p>2010-11-15</p> <p>We studied the formation of surface layers <span class="hlt">hardened</span> by plasma-enhanced oxidation of the silicone elastomer poly(dimethylsiloxane). We explored the largest parameter space surveyed to date. The surface layers may wrinkle, crack, or both, under conditions that at times are controlled by design, but more often have been discovered by trial-and-error. We find four distinct topographies: flat/wrinkled/cracked/cracked and wrinkled. Each topography is clearly separated in the space of plasma dose versus plasma pressure. We analyzed wrinkle amplitude and wavelength by atomic force microscopy in the tapping mode. From these dimensions we calculated the elastic modulus and thickness of the hard surface layer, and inferred a graded hardness, by employing a modified theoretical model. Our main result is the identification of the parameters under which the technologically important pure wrinkled, crack-free topography is obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21371494','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21371494"><span>Theoretical Study of the Oxidation Behavior of Precipitation <span class="hlt">Hardening</span> Steel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pistofidis, N.; Vourlias, G.; Chrissafis, K.; Psyllaki, P.</p> <p>2010-01-21</p> <p>The oxidation of precipitation <span class="hlt">hardening</span> (PH) steels is a rather unexplored area. In the present work an attempt is made is made to estimate the kinetics of a PH steel. For this purpose specimens of the material under examination were isothermally heated at 850, 900 and 950 deg. C for 15 hr. Kinetics was based on TGA results. During heating a thick scale is formed on the substrate surface, which is composed by different oxides. The layer close to the substrate is compact and as a result it impedes corrosion. The mathematical analysis of the collected data shows that the change of the mass of the substrate per unit area versus time is described by a parabolic law.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1334885','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1334885"><span>Identifying Vulnerabilities and <span class="hlt">Hardening</span> Attack Graphs for Networked Systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Saha, Sudip; Vullinati, Anil K.; Halappanavar, Mahantesh; Chatterjee, Samrat</p> <p>2016-09-15</p> <p>We investigate efficient security control methods for protecting against vulnerabilities in networked systems. A large number of interdependent vulnerabilities typically exist in the computing nodes of a cyber-system; as vulnerabilities get exploited, starting from low level ones, they open up the doors to more critical vulnerabilities. These cannot be understood just by a topological analysis of the network, and we use the attack graph abstraction of Dewri et al. to study these problems. In contrast to earlier approaches based on heuristics and evolutionary algorithms, we study rigorous methods for quantifying the inherent vulnerability and <span class="hlt">hardening</span> cost for the system. We develop algorithms with provable approximation guarantees, and evaluate them for real and synthetic attack graphs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860060972&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHardening','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860060972&hterms=Hardening&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHardening"><span>Hydrogen effects on the age <span class="hlt">hardening</span> behavior of 2024 aluminum</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wagner, J. A.; Louthan, M. R., Jr.; Sisson, R. D., Jr.</p> <p>1986-01-01</p> <p>It has been found that the fatigue crack growth rate in aluminum alloys increases significantly in the presence of moisture. This phenomenon along with a moisture effect observed in another context has been attributed to 'embrittlement' of the aluminum by absorbed hydrogen generated by the reaction of moisture with freshly exposed aluminum. A description is given of a number of age <span class="hlt">hardening</span> experiments involving 2024 aluminum. These experiments show that a mechanism related to the segregation of absorbed hydrogen to the coherent theta-double-prime interfaces may account for the observed reduction in fatigue life. It is pointed out that this segregation promotes a loss of coherency in the hydrogen rich region at a fatigue crack tip. Subsequently, the loss of coherency causes local softening and reduces fatigue life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OptEn..54e3106R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OptEn..54e3106R"><span>Protection performance evaluation regarding imaging sensors <span class="hlt">hardened</span> against laser dazzling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ritt, Gunnar; Koerber, Michael; Forster, Daniel; Eberle, Bernd</p> <p>2015-05-01</p> <p>Electro-optical imaging sensors are widely distributed and used for many different purposes, including civil security and military operations. However, laser irradiation can easily disturb their operational capability. Thus, an adequate protection mechanism for electro-optical sensors against dazzling and damaging is highly desirable. Different protection technologies exist now, but none of them satisfies the operational requirements without any constraints. In order to evaluate the performance of various laser protection measures, we present two different approaches based on triangle orientation discrimination on the one hand and structural similarity on the other hand. For both approaches, image analysis algorithms are applied to images taken of a standard test scene with triangular test patterns which is superimposed by dazzling laser light of various irradiance levels. The evaluation methods are applied to three different sensors: a standard complementary metal oxide semiconductor camera, a high dynamic range camera with a nonlinear response curve, and a sensor <span class="hlt">hardened</span> against laser dazzling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16614217','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16614217"><span><span class="hlt">Hardening</span> by annealing and softening by deformation in nanostructured metals.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Xiaoxu; Hansen, Niels; Tsuji, Nobuhiro</p> <p>2006-04-14</p> <p>We observe that a nanostructured metal can be <span class="hlt">hardened</span> by annealing and softened when subsequently deformed, which is in contrast to the typical behavior of a metal. Microstructural investigation points to an effect of the structural scale on fundamental mechanisms of dislocation-dislocation and dislocation-interface reactions, such that heat treatment reduces the generation and interaction of dislocations, leading to an increase in strength and a reduction in ductility. A subsequent deformation step may restore the dislocation structure and facilitate the yielding process when the metal is stressed. As a consequence, the strength decreases and the ductility increases. These observations suggest that for materials such as the nanostructured aluminum studied here, deformation should be used as an optimizing procedure instead of annealing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1013610','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1013610"><span>Method of forming a <span class="hlt">hardened</span> surface on a substrate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Branagan, Daniel J.</p> <p>2010-08-31</p> <p>The invention includes a method of producing a hard metallic material by forming a mixture containing at least 55% iron and at least one of B, C, Si and P. The mixture is formed into an alloy and cooled to form a metallic material having a hardness of greater than about 9.2 GPa. The invention includes a method of forming a wire by combining a metal strip and a powder. The metal strip and the powder are rolled to form a wire containing at least 55% iron and from two to seven additional elements including at least one of C, Si and B. The invention also includes a method of forming a <span class="hlt">hardened</span> surface on a substrate by processing a solid mass to form a powder, applying the powder to a surface to form a layer containing metallic glass, and converting the glass to a crystalline material having a nanocrystalline grain size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015RuMet2015..558K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015RuMet2015..558K"><span>Effective mineral coatings for <span class="hlt">hardening</span> the surface of metallic materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kislov, S. V.; Kislov, V. G.; Skazochkin, A. V.; Bondarenko, G. G.; Tikhonov, A. N.</p> <p>2015-07-01</p> <p>The structural changes that occur in the surface and surface layers of steel 20Kh13 and titanium alloy PT-3V (Russian designation) samples after each stage of <span class="hlt">hardening</span> due to a formed mineral surface layer are studied by optical microscopy, transmission electron microscopy, and scanning electron microscopy. Electric spark alloying, pressing, and ultrasonic processing are used to reach the effect of volume compression of the base metal and the mineral in the plastic deformation zone. As a result, applied mineral particles concentrate in preliminarily created microvoids in a thin surface layer. The surface layer thus modified acquires a high hardness and wear resistance. Durometry shows that the hardness of the processed sample surfaces increases more than twofold. Therefore, the developed technology of creating a mineral coating can be used to increase the tribological properties of the surfaces of the parts, units, and mechanisms of turbine, pump, and mining equipment, which undergo intense wear during operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15047341','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15047341"><span>Characterization and <span class="hlt">hardening</span> of concrete with ultrasonic testing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>del Río, L M; Jiménez, A; López, F; Rosa, F J; Rufo, M M; Paniagua, J M</p> <p>2004-04-01</p> <p>In this study, we describe a technique which can be used to characterize some relevant properties of 26 cylindrical samples (15 x 30 cm2) of concrete. The characterization has been performed, according to Spanish regulations in force, by some destructive and ultrasound-based techniques using frequencies of 40 kHz. Samples were manufactured using different water/cement ratios (w/c), ranging from 0.48 to 0.80, in order to simulate different values of compressive strength at each sample. We have correlated the propagation velocity v of ultrasonic waves through the samples to compressive strength R values. As some other authors remark, there exists an exponential relationship between the two above parameters. We have found that a highly linear relationship is present between R and w/c concentration at the samples. Nevertheless, when the same linear model is adopted to describe the relationship between v and w/c, the value of r decreases significantly. Thus, we have performed a multiple regression analysis which takes into account the impact of different concrete constituents (water, cement, sand, etc.) on ultrasound propagation speed. One of the most relevant practical issues addressed in our study is the estimation of the <span class="hlt">hardening</span> curve of concrete, which can be used to quantify the viability of applying the proposed method in a real scenario. Subsequently, we also show a detailed analysis of the temporal evolution of v and R through 61 days, beginning at the date where the samples were manufactured. After analyzing both parameters separately, a double reciprocal relationship is deduced. Using the above parameters, we develop an NDE-based model which can be used to estimate <span class="hlt">hardening</span> time of concrete samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002iaf..confE.476G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002iaf..confE.476G"><span>Radiation Effects and <span class="hlt">Hardening</span> Techniques for Spacecraft Microelectronics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gambles, J. W.; Maki, G. K.</p> <p>2002-01-01</p> <p>The natural radiation from the Van Allen belts, solar flares, and cosmic rays found outside of the protection of the earth's atmosphere can produce deleterious effects on microelectronics used in space systems. Historically civil space agencies and the commercial satellite industry have been able to utilize components produced in special radiation <span class="hlt">hardened</span> fabrication process foundries that were developed during the 1970s and 1980s under sponsorship of the Departments of Defense (DoD) and Energy (DoE). In the post--cold war world the DoD and DoE push to advance the rad--hard processes has waned. Today the available rad--hard components lag two-plus technology node generations behind state- of-the-art commercial technologies. As a result space craft designers face a large performance gap when trying to utilize available rad--hard components. Compounding the performance gap problems, rad--hard components are becoming increasingly harder to get. Faced with the economic pitfalls associated with low demand versus the ever increasing investment required for integrated circuit manufacturing equipment most sources of rad--hard parts have simply exited this market in recent years, leaving only two domestic US suppliers of digital rad--hard components. This paper summarizes the radiation induced mechanisms that can cause digital microelectronics to fail in space, techniques that can be applied to mitigate these failure mechanisms, and ground based testing used to validate radiation hardness/tolerance. The radiation <span class="hlt">hardening</span> techniques can be broken down into two classes, Hardness By Process (HBP) and Hardness By Design (HBD). Fortunately many HBD techniques can be applied to commercial fabrication processes providing space craft designer with radiation tolerant Application Specific Integrated Circuits (ASICs) that can bridge the performance gap between the special HBP foundries and the commercial state-of-the-art performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6526842','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6526842"><span>Low-temperature tolerance and cold <span class="hlt">hardening</span> of cacti</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nobel, P.S.</p> <p>1982-12-01</p> <p>Reduced uptake by the chlorenchyma cells of cacti of a stain (neutral red) was used as an indicator of low-temperature damage resulting from cooling stems in the laboratory. Necrosis set in a few degrees below the temperature at which the fraction of cells accumulating stain was reduced by 50%. Coryphantha vivipara, Opuntia polyacantha, and Pediocactus simpsonii, which range to over 300 m altitude in southern Wyoming, were quite cold tolerant. Relationships among tissue cold sensitivity, morphological features which protect the stems from low temperatures, and the occurrence of species in progressively colder regions were investigated. Differences in tissue cold sensitivity accounted for the approx. = 600 m higher elevational limit of Coryphantha vivipara var. rosea compared to the morphologically similar var. deserti in southern Nevada. In contrast, morphological differences alone could adequately explain the relative northern limits of the columnar cacti Carnegiea gigantea vs Stenocereus gummosus and the barrel cacti Ferocactus acanthodes vs. F. wislizenii in the southwestern United States, as previously indicated using a computer model. Cold <span class="hlt">hardening</span> in response to decreasing day/night air temperatures was observed for 10 species. A decrease from 50/sup 0//40/sup 0/ to 10/sup 0//0/sup 0/ lowered by 4/sup 0/ the temperature at which the fraction of the chlorenchyma cells taking up stain was reduced 50% for both D. rhodacantha and T. candicans, with a half-time for the shift of approx. = 3 d. The tolerance of subzero temperatures and the ability to cold <span class="hlt">harden</span> allow cacti to range into regions with considerable wintertime freezing.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-09-18/pdf/2013-22688.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-09-18/pdf/2013-22688.pdf"><span>78 FR 57418 - Compliance With Order EA-13-109, Order Modifying Licenses With Regard to Reliable <span class="hlt">Hardened</span>...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-09-18</p> <p>... COMMISSION Compliance With Order EA-13-109, Order Modifying Licenses With Regard to Reliable <span class="hlt">Hardened</span>... Licenses with Regard to Reliable <span class="hlt">Hardened</span> Containment Vents Capable of Operation under Severe Accident...-109, ``Order Modifying Licenses with Regard to Reliable <span class="hlt">Hardened</span> Containment Vents Capable...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD0779534','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD0779534"><span>Slope Stability in the Choco <span class="hlt">Volcanics</span>.</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p></p> <p>The rocks comprising the Choco <span class="hlt">volcanics</span>, a formation crossed by the proposed Route 25 sea-level canal through northwestern Colombia, have been...found to slake in ethylene glycol. It is concluded that the factors of intermediate unconfined compressive strength and slaking will not cause massive slope failures of crater slopes formed in the Choco <span class="hlt">volcanic</span> rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730019636','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730019636"><span>A preliminary evaluation of ERTS-1 images on the <span class="hlt">volcanic</span> areas of Southern Italy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cassinis, R.; Lechi, G. M.</p> <p>1973-01-01</p> <p>The test site selected for the investigation covers nearly all the regions of active and quiescent <span class="hlt">volcanism</span> in southern Italy, i.e. the eastern part of the island of Sicily, the Aeolian Islands and the area of Naples. The three active European volcanoes (Etna, Stromboli and Vesuvius) are included. The investigation is in the frame of a program for the surveillance of active volcanoes by geophysical (including remote sensing thermal methods) and geochemical methods. By the multispectral analysis of ERTS-1 data it is intended to study the spectral behavior of the <span class="hlt">volcanic</span> materials as well as the major geological lineaments with special reference to those associated with the <span class="hlt">volcanic</span> region. Secondary objectives are also the determination of the hydrographic network seasonal behavior and the relationship between the vegetation cover and the different type of <span class="hlt">soils</span> and rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890049129&hterms=ALBANY+OREGON&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DALBANY%2BOREGON','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890049129&hterms=ALBANY+OREGON&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DALBANY%2BOREGON"><span>Petrogenetic modeling of 74220 high-Ti orange <span class="hlt">volcanic</span> glasses and the Apollo 11 and 17 high-Ti mare basalts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hughes, S. S.; Schmitt, R. A.; Delano, J. W.</p> <p>1989-01-01</p> <p>An INAA analysis of 16 individual spherules of orange <span class="hlt">volcanic</span> glass extracted from the 74220,680 <span class="hlt">soil</span> was performed in order to determine trace element signatures in a primary high-Ti mare magma. The composition of these glasses is shown to be nearly identical to that of 74220 bulk <span class="hlt">soil</span>, indicating a general absence of constituents other than <span class="hlt">volcanic</span> glass in the <span class="hlt">soil</span>. The results suggest that the evolving lunar mantle included processes of cumulate-mass transport and/or segregation of the primordial lunar magma ocean into separate differentiating zones, allowing commingling of early and late components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1111726C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1111726C"><span>Hydrogeology of the Azores <span class="hlt">volcanic</span> archipelago (Portugal)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cruz, J.; Coutinho, R.; Antunes, P.; Freire, P.</p> <p>2009-04-01</p> <p>The archipelago of the Azores is made of nine islands of <span class="hlt">volcanic</span> origin located in the North Atlantic Ocean, with an area of 2333 km2 and approximately 237500 inhabitants, which are 98% dependant from groundwater sources for their water consumption. Therefore, groundwater is a resource that plays a vital role as drinking water source and as ecosystem support matrix. Nevertheless, besides the environmental, social and economical value of groundwater, this resource is subject to an increase pressure and in several islands water quality deterioration is shown by monitoring data. This pressure is also shown by the 42.7% increase expected for domestic use until the year 2020 at the Azores, with higher groundwater abstraction. The Azores climate can be considered as marine temperate, which is reflected by the low thermal amplitude and high precipitation. A well-established difference between a dry season and a colder and wet season occurs, as from October to March about 75% of the annual precipitation is registered. The average annual precipitation at the Azores is 1930 mm, exceeding by far the average annual actual evapotranspiration, which is 581 mm. Recharge rates range from 8.5% to 62.1%, and the highest values are observed at Pico, Terceira, Faial, São Miguel and Graciosa islands, especially in areas where the terrain is covered by recent basaltic lava flows and the <span class="hlt">soil</span> cover is sparse. Groundwater resources estimates point to a total volume of about 1600x106 m3/yr. Values above the recharge median, equal to 101.3x106 m3/yr. were estimated for the São Miguel, São Jorge, Terceira and Flores islands. Despite differences in the islands growth, as a result of successive <span class="hlt">volcanic</span> eruptions of various types, groundwater occurrence can be described in function of two main aquifers systems: (1) the basal aquifer system, which corresponds to fresh-water lenses floating on underlying salt water, and (2) perched-water bodies, which are usually drained by springs spread in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009Icar..204..239V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009Icar..204..239V"><span>Io: Heat flow from dark <span class="hlt">volcanic</span> fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Veeder, Glenn J.; Davies, Ashley Gerard; Matson, Dennis L.; Johnson, Torrence V.</p> <p>2009-11-01</p> <p>Dark flow fields on the jovian satellite Io are evidence of current or recent <span class="hlt">volcanic</span> activity. We have examined the darkest <span class="hlt">volcanic</span> fields and quantified their thermal emission in order to assess their contribution to Io's total heat flow. Loki Patera, the largest single source of heat flow on Io, is a convenient point of reference. We find that dark <span class="hlt">volcanic</span> fields are more common in the hemisphere opposite Loki Patera and this large scale concentration is manifested as a maximum in the longitudinal distribution (near ˜200 °W), consistent with USGS global geologic mapping results. In spite of their relatively cool temperatures, dark <span class="hlt">volcanic</span> fields contribute almost as much to Io's heat flow as Loki Patera itself because of their larger areal extent. As a group, dark <span class="hlt">volcanic</span> fields provide an asymmetric component of ˜5% of Io's global heat flow or ˜5 × 10 12 W.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017FrES..tmp....6C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017FrES..tmp....6C"><span>Sediment transport in headwaters of a <span class="hlt">volcanic</span> catchment—Kamchatka Peninsula case study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chalov, Sergey R.; Tsyplenkov, Anatolii S.; Pietron, Jan; Chalova, Aleksandra S.; Shkolnyi, Danila I.; Jarsjö, Jerker; Maerker, Michael</p> <p>2017-01-01</p> <p>Due to specific environmental conditions, headwater catchments located on <span class="hlt">volcanic</span> slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring causes that the governing processes and patterns in these areas are rarely well understood. In this study, spatiotemporal water discharge and sediment transport from upstream sources was investigated in one of the numerous headwater catchments located in the lahar valleys of the Kamchatka Peninsula Sukhaya Elizovskaya River near Avachinskii and Koryakskii volcanoes. Three different subcatchments and corresponding channel types (wandering rivers within lahar valleys, mountain rivers within <span class="hlt">volcanic</span> slopes and rivers within submountain terrains) were identified in the studied area. Our measurements from different periods of observations between years 2012-2014 showed that the studied catchment was characterized by extreme diurnal fluctuation of water discharges and sediment loads that were influenced by snowmelt patterns and high infiltration rates of the easily erodible lahar deposits. The highest recorded sediment loads were up to 9•104 mg/L which was related to an increase of two orders of magnitude within a one day of observations. Additionally, to get a quantitative estimate of the spatial distribution of the eroded material in the <span class="hlt">volcanic</span> substrates we applied an empirical <span class="hlt">soil</span> erosion and sediment yield model-modified universal <span class="hlt">soil</span> loss equation (MUSLE). The modeling results showed that even if the applications of the universal erosion model to different non-agricultural areas (e.g., <span class="hlt">volcanic</span> catchments) can lead to irrelevant results, the MUSLE model delivered might be acceptable for non-lahar areas of the studied <span class="hlt">volcanic</span> catchment. Overall the results of our study increase our understanding of the hydrology and associated sediment transport for prediction of risk management within headwater <span class="hlt">volcanic</span> catchments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970041182','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970041182"><span>Large <span class="hlt">Volcanic</span> Rises on Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smrekar, Suzanne E.; Kiefer, Walter S.; Stofan, Ellen R.</p> <p>1997-01-01</p> <p>Large <span class="hlt">volcanic</span> rises on Venus have been interpreted as hotspots, or the surface manifestation of mantle upwelling, on the basis of their broad topographic rises, abundant <span class="hlt">volcanism</span>, and large positive gravity anomalies. Hotspots offer an important opportunity to study the behavior of the lithosphere in response to mantle forces. In addition to the four previously known hotspots, Atla, Bell, Beta, and western Eistla Regiones, five new probable hotspots, Dione, central Eistla, eastern Eistla, Imdr, and Themis, have been identified in the Magellan radar, gravity and topography data. These nine regions exhibit a wider range of volcano-tectonic characteristics than previously recognized for venusian hotspots, and have been classified as rift-dominated (Atla, Beta), coronae-dominated (central and eastern Eistla, Themis), or volcano-dominated (Bell, Dione, western Eistla, Imdr). The apparent depths of compensation for these regions ranges from 65 to 260 km. New estimates of the elastic thickness, using the 90 deg and order spherical harmonic field, are 15-40 km at Bell Regio, and 25 km at western Eistla Regio. Phillips et al. find a value of 30 km at Atla Regio. Numerous models of lithospheric and mantle behavior have been proposed to interpret the gravity and topography signature of the hotspots, with most studies focusing on Atla or Beta Regiones. Convective models with Earth-like parameters result in estimates of the thickness of the thermal lithosphere of approximately 100 km. Models of stagnant lid convection or thermal thinning infer the thickness of the thermal lithosphere to be 300 km or more. Without additional constraints, any of the model fits are equally valid. The thinner thermal lithosphere estimates are most consistent with the <span class="hlt">volcanic</span> and tectonic characteristics of the hotspots. Estimates of the thermal gradient based on estimates of the elastic thickness also support a relatively thin lithosphere (Phillips et al.). The advantage of larger estimates of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.6701P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.6701P"><span>Assessing <span class="hlt">volcanic</span> hazards with Vhub</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palma, J. L.; Charbonnier, S.; Courtland, L.; Valentine, G.; Connor, C.; Connor, L.</p> <p>2012-04-01</p> <p>Vhub (online at vhub.org) is a virtual organization and community cyberinfrastructure designed for collaboration in volcanology research, education, and outreach. One of the core objectives of this project is to accelerate the transfer of research tools to organizations and stakeholders charged with volcano hazard and risk mitigation (such as volcano observatories). Vhub offers a clearinghouse for computational models of <span class="hlt">volcanic</span> processes and data analysis, documentation of those models, and capabilities for online collaborative groups focused on issues such as code development, configuration management, benchmarking, and validation. Vhub supports computer simulations and numerical modeling at two levels: (1) some models can be executed online via Vhub, without needing to download code and compile on the user's local machine; (2) other models are not available for online execution but for offline use in the user's computer. VHub also has wikis, blogs and group functions around specific topics to encourage collaboration, communication and discussion. Some of the simulation tools currently available to Vhub users are: Energy Cone (rapid delineation of the impact zone by pyroclastic density currents), Tephra2 (tephra dispersion forecast tool), Bent (atmospheric plume analysis), Hazmap (simulate sedimentation of <span class="hlt">volcanic</span> particles) and TITAN2D (mass flow simulation tool). The list of online simulations available on Vhub is expected to expand considerably as the volcanological community becomes more involved in the project. This presentation focuses on the implementation of online simulation tools, and other Vhub's features, for assessing <span class="hlt">volcanic</span> hazards following approaches similar to those reported in the literature. Attention is drawn to the minimum computational resources needed by the user to carry out such analyses, and to the tools and media provided to facilitate the effective use of Vhub's infrastructure for hazard and risk assessment. Currently the project</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090007932&hterms=Hardening&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DHardening','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090007932&hterms=Hardening&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DHardening"><span>Tradeoffs in Flight Design Upset Mitigation in State of the Art FPGAs: <span class="hlt">Hardened</span> by Design vs. Design Level <span class="hlt">Hardening</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Swift, Gary M.; Roosta, Ramin</p> <p>2004-01-01</p> <p>This presentation compares and contrasts the effectiveness and the system/designer impacts of the two main approaches to upset <span class="hlt">hardening</span>: the Actel approach (RTSX-S and RTAX-S) of low-level (inside each flip-flop) triplication and the Xilinx approach (Virtex and Virtex2) of design-level triplication of both functional blocks and voters. The effectiveness of these approaches is compared using measurements made in conjunction with each of the FPGAs' manufacturer: for Actel, published data [1] and for Xilinx, recent results from the Xilinx SEE Test Consortium (note that the author is an active and founding member). The impacts involve Actel advantages in the areas of transistor-utilization efficiency and minimizing designer involvement in the triplication while the Xilinx advantages relate to the ability to custom tailor upset hardness and the flexibility of re-configurability. Additionally, there are currently clear Xilinx advantages in available features such as the number of I/O's, logic cells, and RAM blocks as well as speed. However, the advantage of the Actel anti-fuses for configuration over the Xilinx SRAM cells is that the latter need additional functionality and external circuitry (PROMs and, at least a watchdog timer) for configuration and configuration scrubbing. Further, although effectively mitigated if done correctly, the proton upset-ability of the Xilinx FPGAs is a concern in severe proton-rich environments. Ultimately, both manufacturers' upset <span class="hlt">hardening</span> is limited by SEFI (single-event functional interrupt) rates where it appears the Actel results are better although the Xilinx Virtex2-family result of about one SEFI in 65 device-years in solar-min GCR (the more intense part of the galactic cosmic-ray background) should be acceptable to most missions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27794445','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27794445"><span>Heavy metals in the <span class="hlt">volcanic</span> environment and thyroid cancer.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vigneri, R; Malandrino, P; Gianì, F; Russo, M; Vigneri, P</p> <p>2016-10-26</p> <p>In the last two decades thyroid cancer incidence has increased worldwide more than any other cancer. Overdiagnosis of subclinical microcarcinomas has certainly contributed to this increase but many evidences indicate that a true increase, possibly due to environmental factors, has also occurred. Thyroid cancer incidence is markedly increased in <span class="hlt">volcanic</span> areas. Thus, the <span class="hlt">volcanic</span> environment is a good model to investigate the possible factors favoring thyroid cancer. In the <span class="hlt">volcanic</span> area of Mt. Etna in Sicily, as well as in other <span class="hlt">volcanic</span> areas, a non-anthropogenic pollution with heavy metals has been documented, a consequence of gas, ash and lava emission. <span class="hlt">Soil</span>, water and atmosphere contamination, via the food chain, biocontaminate the residents as documented by high levels in the urines and the scalp hair compared to individuals living in adjacent non-<span class="hlt">volcanic</span> areas. Trace amounts of metals are essential nutrients but, at higher concentrations, can be toxic for living cells. Metals can behave both as endocrine disruptors, perturbing the hormonal system, and as carcinogens, promoting malignant transformation. Similarly to other carcinogens, the transforming effect of heavy metals is higher in developing organisms as the fetus (contaminated via the mother) and individuals in early childhood. In the last decades environment metal pollution has greatly increased in industrialized countries. Although still within the "normal" limits for each single metal the hormesis effect (heavy metal activity at very low concentration because of biphasic, non linear cell response) and the possible potentiation effect resulting from the mixture of different metals acting synergistically can explain cell damage at very low concentrations. The effect of metals on the human thyroid is poorly studied: for some heavy metals no data are available. The scarce studies that have been performed mainly focus on metal effect as thyroid endocrine disruptors. The metal concentration in tissues has</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997MMTA...28..775K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997MMTA...28..775K"><span>Secondary <span class="hlt">hardening</span> and fracture behavior in alloy steels containing Mo, W, and Cr</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwon, H.; Lee, K. B.; Yang, H. R.; Lee, J. B.; Kim, Y. S.</p> <p>1997-03-01</p> <p>In 4Mo, 6W, 2Mo3W, 2Mo2Cr, and 3W2Cr alloy steels, which cointain alloying elements, such as Mo, W and Cr, contributing to the secondary <span class="hlt">hardening</span> by forming M2C type carbide, the secondary <span class="hlt">hardening</span> and fracture behavior were studied. Molybdenum had a strong effect on secondary <span class="hlt">hardening</span>, while W had a very weak effect on it but delayed the overaging. The MoW steel exhibited both moderately strong <span class="hlt">hardening</span> and considerable resistance to overaging. On the other hand, the secondary <span class="hlt">hardening</span> effect was diminished by the Cr addition, because the cementite of M3C type was stabilized at higher temperatures and the formation of M2C carbides was thus inhibited. Although the Cr addition had no merit in the secondary <span class="hlt">hardening</span> itself, it eliminated the secondary <span class="hlt">hardening</span> embrittlement (SHE). This was observed as a severe intergranular embrittlement due to the impurity segregation for the Mo and MoW steels and as a decrease in upper shelf energy for W steel, even in the overaged condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17884085','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17884085"><span>Brief carbon dioxide exposure blocks heat <span class="hlt">hardening</span> but not cold acclimation in Drosophila melanogaster.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Milton, Claire C; Partridge, Linda</p> <p>2008-01-01</p> <p>Carbon dioxide is a commonly used anaesthetic in Drosophila research. While any detrimental effects of CO2 exposure on behaviour or traits are largely unknown, a recent study observed significant effects of CO2 exposure on rapid cold <span class="hlt">hardening</span> and chill-coma recovery in Drosophila melanogaster. In this study we investigated the effect of a brief CO2 exposure on heat <span class="hlt">hardening</span> and cold acclimation in D. melanogaster, measuring heat knockdown and chill-coma recovery times of flies exposed to CO2 for 1 min after <span class="hlt">hardening</span> or acclimation. CO2 anaesthesia had a significant negative effect on heat <span class="hlt">hardening</span>, with heat knockdown rates in <span class="hlt">hardened</span> flies completely reduced to those of controls after CO2 exposure. Chill-coma recovery rates also significantly increased in acclimated flies that were exposed to CO2, although not to the same extent seen in the heat populations. CO2 exposure had no impact on heat knockdown rates of control flies, while there was a significant negative effect of the anaesthetic on chill-coma recovery rates of control flies. In light of these results, we suggest that CO2 should not be used after <span class="hlt">hardening</span> in heat resistance assays due to the complete reversal of the heat <span class="hlt">hardening</span> process upon exposure to CO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23863406','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23863406"><span>Identification of potential oviductal factors responsible for zona pellucida <span class="hlt">hardening</span> and monospermy during fertilization in mammals.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mondéjar, Irene; Martínez-Martínez, Irene; Avilés, Manuel; Coy, Pilar</p> <p>2013-09-01</p> <p>Oviduct fluid increases the time required for digestion of the zona pellucida (ZP) by proteolytic enzymes (ZP <span class="hlt">hardening</span>). This effect has been associated with levels of monospermy after in vitro fertilization (IVF) in the pig and cow, but the possible existence of a directly proportional relationship between <span class="hlt">hardening</span> and monospermy remains unknown. To investigate whether variations in <span class="hlt">hardening</span> of different oviductal fluids (OFs) are correlated with variations in levels of monospermy after IVF, porcine oocytes were incubated with three batches of OFs known to produce different ZP <span class="hlt">hardening</span> effects (3, 7, and 25 min); after IVF, monospermy levels were 0%, 14.58% ± 5.14%, and 35.14% ± 7.95%, respectively. These results could partially explain the lack of polyspermy found during in vivo fertilization in pigs (with a <span class="hlt">hardened</span> oviductal ZP) compared with levels found during IVF (with no <span class="hlt">hardened</span> ZP). Using the bovine model, OF was fractionated by heparin affinity chromatography, and the <span class="hlt">hardening</span> effect on the ZP was tested for each fraction obtained from a linear gradient of sodium chloride concentration. The highest effect was obtained with the fraction eluted with 0.4 M sodium chloride. Fractions with high-level or low-level effects were processed by on-chip electrophoresis and high-performance liquid chromatography-tandem mass spectrometry. A list of potential proteins responsible for this effect includes OVGP1 and members of the HSP and PDI families.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JNuM..481..117Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JNuM..481..117Y"><span>Investigation on microstructural evolution and <span class="hlt">hardening</span> mechanism in dilute Zrsbnd Nb binary alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, H. L.; Matsukawa, Y.; Kano, S.; Duan, Z. G.; Murakami, K.; Abe, H.</p> <p>2016-12-01</p> <p>In this study, the microstructural changes induced by doping of Nb in Zr were investigated by the combined utilization of electron backscatter diffraction and electron transmission microscopy techniques, followed by the correlated <span class="hlt">hardening</span> mechanism being elucidated based on the obtained microstructural parameters. Microstructural characterization results revealed that microstructural changes caused by doping of Nb in Zr were mainly embodied via two aspects: reducing the matrix α-Zr grain size and increasing the amount of β-Nb particles. β-phase stabilizing effect, dragging effect and pinning effect introduced and enhanced by Nb addition, worked together to significantly reduce the grain size in Zr-Nb alloys. β-Nb particles were firstly observed in Zr0.5Nb specimen with the fairly low number density of ∼2.0 × 1018/m3, then this value explosively increased to ∼3.3 × 1020/m3 for Zr2Nb specimen. In addition, hardness was increased with an increase in the Nb content. The <span class="hlt">hardening</span> contributions from solid solution <span class="hlt">hardening</span>, grain boundary <span class="hlt">hardening</span> and precipitation <span class="hlt">hardening</span> were quantitatively estimated as per the obtained microstructural parameters. Results inferred that solid solution <span class="hlt">hardening</span> contributed the majority when the Nb atoms were solid dissolved (≤0.5 wt%), whereas the precipitation <span class="hlt">hardening</span> surpassed any other factors when the β-Nb particles were steadily precipitated (≥1 wt%).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MMTA...46.3761S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MMTA...46.3761S"><span>Analysis of Obstacle <span class="hlt">Hardening</span> Models Using Dislocation Dynamics: Application to Irradiation-Induced Defects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sobie, Cameron; Bertin, Nicolas; Capolungo, Laurent</p> <p>2015-08-01</p> <p>Irradiation <span class="hlt">hardening</span> in -iron represents a critical factor in nuclear reactor design and lifetime prediction. The dispersed barrier <span class="hlt">hardening</span>, Friedel Kroupa Hirsch (FKH), and Bacon Kocks Scattergood (BKS) models have been proposed to predict <span class="hlt">hardening</span> caused by dislocation obstacles in metals, but the limits of their applicability have never been investigated for varying defect types, sizes, and densities. In this work, dislocation dynamics calculations of irradiation-induced obstacle <span class="hlt">hardening</span> in the athermal case were compared to these models for voids, self-interstitial atom (SIA) loops, and a combination of the two types. The BKS model was found to accurately predict <span class="hlt">hardening</span> due to voids, whereas the FKH model was superior for SIA loops. For both loops and voids, the <span class="hlt">hardening</span> from a normal distribution of defects was compared to that from the mean size, and was shown to have no statistically significant dependence on the distribution. A mean size approach was also shown to be valid for an asymmetric distribution of voids. A non-linear superposition principle was shown to predict the <span class="hlt">hardening</span> from the simultaneous presence of voids and SIA loops.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JNuM..417..949F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JNuM..417..949F"><span>Effects of solute elements on irradiation <span class="hlt">hardening</span> and microstructural evolution in low alloy steels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujii, Katsuhiko; Ohkubo, Tadakatsu; Fukuya, Koji</p> <p>2011-10-01</p> <p>The effects of the elements Mn, Ni, Si and Cu on irradiation <span class="hlt">hardening</span> and microstructural evolution in low alloy steels were investigated in ion irradiation experiments using five kinds of alloys prepared by removing Mn, Ni and Si from, and adding 0.05 wt.%Cu to, the base alloy (Fe-1.5Mn-0.5Ni-0.25Si). The alloy without Mn showed less <span class="hlt">hardening</span> and the alloys without Ni or Si showed more <span class="hlt">hardening</span>. The addition of Cu had hardly any influence on <span class="hlt">hardening</span>. These facts indicated that Mn enhanced <span class="hlt">hardening</span> and that Ni and Si had some synergetic effects. The formation of solute clusters was not confirmed by atom probe (AP) analysis, whereas small dislocation loops were identified by TEM observation. The difference in <span class="hlt">hardening</span> between the alloys with and without Mn was qualitatively consistent with loop formation. However, microstructural components that were not detected by the AP and TEM were assumed to explain the <span class="hlt">hardening</span> level quantitatively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740017769','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740017769"><span>An atlas of <span class="hlt">volcanic</span> ash</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Heiken, G.</p> <p>1974-01-01</p> <p><span class="hlt">Volcanic</span> ash samples collected from a variety of recent eruptions were studied, using petrography, chemical analyses, and scanning electron microscopy to characterize each ash type and to relate ash morphology to magma composition and eruption type. The ashes are best placed into two broad genetic categories: magnetic and hydrovolcanic (phreatomagmatic). Ashes from magmatic eruptions are formed when expanding gases in the magma form a froth that loses its coherence as it approaches the ground surface. During hydrovolcanic eruptions, the magma is chilled on contact with ground or surface waters, resulting in violent steam eruptions. Within these two genetic categories, ashes from different magma types can be characterized. The pigeon hole classification used here is for convenience; there are eruptions which are driven by both phreatic and magmatic gases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ChJME.tmp...25C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ChJME.tmp...25C"><span>Work <span class="hlt">Hardening</span> Behavior of 1020 Steel During Cold-Beating Simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>CUI, Fengkui; LING, Yuanfei; XUE, Jinxue; LIU, Jia; LIU, Yuhui; LI, Yan</p> <p>2017-03-01</p> <p>The present research of cold-beating formation mainly focused on roller design and manufacture, kinematics, constitutive relation, metal flow law, thermo-mechanical coupling, surface micro-topography and microstructure evolution. However, the research on surface quality and performance of workpieces in the process of cold-beating is rare. Cold-beating simulation experiment of 1020 steel is conducted at room temperature and strain rates ranging from 2000 to 4000 s-1 base on the law of plastic forming. According to the experimental data, the model of strain <span class="hlt">hardening</span> of 1020 steel is established, Scanning Electron Microscopy(SEM) is conducted, the mechanism of the work <span class="hlt">hardening</span> of 1020 steel is clarified by analyzing microstructure variation of 1020 steel. It is found that the strain rate <span class="hlt">hardening</span> effect of 1020 steel is stronger than the softening effect induced by increasing temperatures, the process of simulation cold-beating cause the grain shape of 1020 steel significant change and microstructure elongate significantly to form a fibrous tissue parallel to the direction of deformation, the higher strain rate, the more obvious grain refinement and the more <span class="hlt">hardening</span> effect. Additionally, the change law of the work <span class="hlt">hardening</span> rate is investigated, the relationship between dislocation density and strain, the relationship between work <span class="hlt">hardening</span> rate and dislocation density is obtained. Results show that the change trend of the work <span class="hlt">hardening</span> rate of 1020 steel is divided into two stages, the work <span class="hlt">hardening</span> rate decreases dramatically in the first stage and slowly decreases in the second stage, finally tending toward zero. Dislocation density increases with increasing strain and strain rate, work <span class="hlt">hardening</span> rate decreases with increasing dislocation density. The research results provide the basis for solving the problem of improving the surface quality and performance of workpieces under cold-beating formation of 1020 steel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22476046','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22476046"><span>Effects of Ce additions on the age <span class="hlt">hardening</span> response of Mg–Zn alloys</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Langelier, Brian Esmaeili, Shahrzad</p> <p>2015-03-15</p> <p>The effects of Ce additions on the precipitation <span class="hlt">hardening</span> behaviour of Mg–Zn are examined for a series of alloys, with Ce additions at both alloying and microalloying levels. The alloys are artificially aged, and studied using hardness measurement and X-ray diffraction, as well as optical and transmission electron microscopy. It is found that the age-<span class="hlt">hardening</span> effect is driven by the formation of fine precipitates, the number density of which is related to the Zn content of the alloy. Conversely, the Ce content is found to slightly reduce <span class="hlt">hardening</span>. When the alloy content of Ce is high, large secondary phase particles containing both Ce and Zn are present, and remain stable during solutionizing. These particles effectively reduce the amount of Zn available as solute for precipitation, and thereby reduce <span class="hlt">hardening</span>. Combining hardness results with thermodynamic analysis of alloy solute levels also suggests that Ce can have a negative effect on <span class="hlt">hardening</span> when present as solutes at the onset of ageing. This effect is confirmed by designing a pre-ageing heat treatment to preferentially remove Ce solutes, which is found to restore the <span class="hlt">hardening</span> capability of an Mg–Zn–Ce alloy to the level of the Ce-free alloy. - Highlights: • The effects of Ce additions on precipitation in Mg–Zn alloys are examined. • Additions of Ce to Mg–Zn slightly reduce the age-<span class="hlt">hardening</span> response. • Ce-rich secondary phase particles deplete the matrix of Zn solute. • <span class="hlt">Hardening</span> is also decreased when Ce is present in solution. • Pre-ageing to preferentially precipitate out Ce restores <span class="hlt">hardening</span> capabilities.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.U42B..07L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.U42B..07L"><span>Feedback Between <span class="hlt">Volcanism</span> and Milankovitch Cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Langmuir, C. H.; Huybers, P.</p> <p>2008-12-01</p> <p>Deglaciation is known to induce <span class="hlt">volcanism</span> in many regions, notably Iceland. Since <span class="hlt">volcanism</span> contributes CO2 to the atmosphere, we have investigated the global extent of glacially induced magmatism, and whether such <span class="hlt">volcanism</span> may contribute to the co-variation between atmospheric CO2 and glacial cycles over the course of the late Pleistocene. Investigation of two combined global data sets on dated eruptions shows that global frequency of subaerial <span class="hlt">volcanic</span> events increases substantially between 12Ka and 7Ka. An important aspect of the data is the temporal bias. While the record extends to 40,000 years, 80% of dated eruptions occur in the last 1000 years. The observation appears robust despite the temporal bias because it is apparent when comparing the 12-7Ka data with both older and younger time intervals. Application of a correction for the temporal bias indicates that global <span class="hlt">volcanic</span> activity increases by a factor of 3-5 during this time interval. Increased <span class="hlt">volcanism</span> can be confidently linked to deglaciation both in terms of location and mechanism. All of the increase occurs in regions thought to have experienced significant deglaciation, that is, predominantly high latitude or high elevation regions with significant precipitation. We show that two possible mechanisms may be important. As previously known from Iceland, deglaciation leads to decompression melting of the underlying mantle, yielding more magmatic input to volcanoes beneath ablating ice. In addition, pacing of <span class="hlt">volcanic</span> eruptions reflects a balance between the forces generated by melt production and degassing, and the confining pressure and integrity of the surrounding rocks. A simple pacing model based on an eruption threshold and observed power law behavior of eruption frequency with number of volcanoes shows that ice volumes changes (estimated from oceanic δ18O) could also cluster the timing of <span class="hlt">volcanic</span> eruptions near times of deglaciation. The influence of deglaciation upon <span class="hlt">volcanism</span> is thus</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EL....10846004Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EL....10846004Z"><span>Experimental insight into the cyclic softening/<span class="hlt">hardening</span> behavior of austenitic stainless steel using ultrasonic higher harmonics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Jianfeng; Xuan, Fu-zhen; Xiang, Yanxun; Zhao, Peng</p> <p>2014-11-01</p> <p>The correlation of cyclic <span class="hlt">hardening</span>/softening behavior of 304 stainless steel (SS) was investigated using nonlinear ultrasonic wave technique. Results reveal that primary <span class="hlt">hardening</span> leads to the increase of acoustic nonlinearity, while secondary <span class="hlt">hardening</span> causes the reverse tendency. This distinct phenomenon is governed by two competitive mechanisms: in the primary-<span class="hlt">hardening</span> stage, the ascended acoustic nonlinearity is related to the increase of planar dislocation structures. While in the second-<span class="hlt">hardening</span> stage, the decrease of acoustic nonlinearity is partly caused by the development of cell structures. In addition, the deformation-induced martensitic transformation also contributes to the increase of acoustic nonlinearity under higher stress amplitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6145987','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6145987"><span>Oil-bearing sediments beneath San Juan <span class="hlt">volcanics</span> - Colorado's newest frontier</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gries, R.R.</p> <p>1985-05-01</p> <p>During the Tertiary, the western part of the northern Sange de Cristo Range dropped 16,000 ft (4877 m) to become what is now known as the San Luis basin. The foreland basin formerly adjacent to and west of the range remained intact but was subsequently concealed by 10,000 ft (3048 m) of <span class="hlt">volcanic</span> deposits. The existence of this concealed basin, a northeastern arm of the San Juan basin, was first suggested by Vincent Kelly who named it the San Juan sag. Oil, which was generated in the underlying Mancos Shale, migrated upward into vesicles and fractures in <span class="hlt">volcanic</span> rocks. In at least two places, oil is currently seeping onto the <span class="hlt">volcanic</span> surface or into overlying <span class="hlt">soil</span>. These oil occurrences encouraged geologic and geophysical exploration and have led to confirmation by drilling that the basin exists. Porous reservoirs in both tertiary sedimentary rocks and <span class="hlt">volcanic</span> rocks overlie a 2000 ft (610 m) Cretaceous Mancos Shale source rock. Within the Mancos Shale are fractured reservoirs, <span class="hlt">volcanic</span> sills that have reservoir potential where fractured or porous, and stray sandstones. The Dakota Formation underlies the Mancos Shale and is about 200 ft (61 m) thick in this area. In addition, the Jurassic section has potential for source rocks in the Todilto Formation and reservoir rocks in the Entrada and Junction Creek Sandstones. The San Juan sag, a newly discovered basin of 2600 miS (6734 kmS) is a frontier for Colorado oil and gas exploration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BVol...79...27D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BVol...79...27D"><span>Contrasting origin of two clay-rich debris flows at Cayambe <span class="hlt">Volcanic</span> Complex, Ecuador</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Detienne, M.; Delmelle, P.; Guevara, A.; Samaniego, P.; Opfergelt, S.; Mothes, P. A.</p> <p>2017-04-01</p> <p>We investigate the sedimentological and mineralogical properties of a debris flow deposit west of Cayambe <span class="hlt">Volcanic</span> Complex, an ice-clad edifice in Ecuador. The deposit exhibits a matrix facies containing up to 16 wt% of clays. However, the stratigraphic relationship of the deposit with respect to the Canguahua Formation, a widespread indurated volcaniclastic material in the Ecuadorian inter-Andean Valley, and the deposit alteration mineralogy differ depending on location. Thus, two different deposits are identified. The Río Granobles debris flow deposit ( 1 km3) is characterised by the alteration mineral assemblage smectite + jarosite, and sulphur isotopic analyses point to a supergene hydrothermal alteration environment. This deposit probably derives from a debris avalanche initiated before 14-21 ka by collapse of a hydrothermally altered rock mass from the volcano summit. In contrast, the alteration mineralogy of the second debris flow deposit, which may itself comprise more than one unit, is dominated by halloysite + smectite and relates to a shallower and more recent (<13 ky) mass movement of high-altitude (>3200 m) <span class="hlt">volcanic</span> <span class="hlt">soils</span>. Our study reinforces the significance of hydrothermal alteration in weakening volcano flanks and in favouring rapid transformation of a <span class="hlt">volcanic</span> debris avalanche into a clay-rich debris flow. It also demonstrates that mineralogical analysis provides crucial information for resolving the origin of a debris flow deposit in <span class="hlt">volcanic</span> terrains. Finally, we posit that slope instability, promoted by ongoing subglacial hydrothermal alteration, remains a significant hazard at Cayambe <span class="hlt">Volcanic</span> Complex.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24907733','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24907733"><span>Structural characterisation of oxygen diffusion <span class="hlt">hardened</span> alpha-tantalum PVD-coatings on titanium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hertl, C; Koll, L; Schmitz, T; Werner, E; Gbureck, U</p> <p>2014-08-01</p> <p>Titanium substrates were coated with tantalum layers of 5 μm thickness using physical vapour deposition (PVD). The tantalum layers showed a (110)-preferred orientation. The coated samples were <span class="hlt">hardened</span> by oxygen diffusion. Using X-ray diffraction the crystallographic structure of the tantalum coatings was characterised, comparing untreated and diffusion <span class="hlt">hardened</span> specimen conditions. Oxygen depth profiles were determined by glow discharge spectrometry. The <span class="hlt">hardening</span> effect of the heat treatment was examined by Vickers microhardness testing. The increase of surface hardness caused by oxygen diffusion was at least 50%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992JPS....38...49G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992JPS....38...49G"><span>Age-<span class="hlt">hardening</span> of grid alloys and its effect on battery manufacturing processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gillian, Warren F.; Rice, David M.</p> <p></p> <p>The age-<span class="hlt">hardening</span> behaviour of three generic classes of lead—antimony grid alloys commonly used in the lead/acid battery manufacturing industry were studied. The effects on age-<span class="hlt">hardening</span> behaviour of several heat treatments devised to simulate downstream processing of battery grids in the manufacturing process were investigated together with the effect of varying cooling rate following casting. Rapid cooling (water quenching) resulted in a general acceleration and enhancement of the age-<span class="hlt">hardening</span> behaviour of all alloys, whilst heat treatment following casting generally gave rise to a reduction in peak hardness.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1806k0008T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1806k0008T"><span>Local <span class="hlt">hardening</span> evaluation of carbon steels by using frequency sweeping excitation and spectrogram method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsuchida, Yuji; Kudo, Yuki; Enokizono, Masato</p> <p>2017-02-01</p> <p>This paper presents our proposed frequency sweeping excitation and spectrogram method (FSES method) by a magnetic sensor for non-destructive testing of <span class="hlt">hardened</span> low carbon steels. This method can evaluate the magnetic properties of low carbon steels which were changed after induction heating treatment. It was examined by our proposed method that the degrees of yield strength of low carbon steels were varied depending on <span class="hlt">hardened</span> conditions. Moreover, it was made clear that the maximum magnetic field strength, Hmax, derived from the measured B-H loops was very sensitive to the <span class="hlt">hardening</span> if the surface of the samples were flat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070036667','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070036667"><span>Developments in Radiation-<span class="hlt">Hardened</span> Electronics Applicable to the Vision for Space Exploration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keys, Andrew S.; Frazier, Donald O.; Patrick , Marshall C.; Watson, Michael D.; Johnson, Michael A.; Cressler, John D.; Kolawa, Elizabeth A.</p> <p>2007-01-01</p> <p>The Radiation <span class="hlt">Hardened</span> Electronics for Space Exploration (RHESE) project develops the advanced technologies required to produce radiation <span class="hlt">hardened</span> electronics, processors, and devices in support of the anticipated requirements of NASA's Constellation program. Methods of protecting and <span class="hlt">hardening</span> electronics against the encountered space environment are discussed. Critical stages of a spaceflight mission that are vulnerable to radiation-induced interruptions or failures are identified. Solutions to mitigating the risk of radiation events are proposed through the infusion of RHESE technology products and deliverables into the Constellation program's spacecraft designs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991hemm.rept..120S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991hemm.rept..120S"><span><span class="hlt">Hardening</span>/finishing treatment of compressor blades using a machine with planetary container motion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shpatakovskii, A. F.</p> <p></p> <p>A process for the <span class="hlt">hardening</span> and finishing of high-pressure compressor blades for aircraft powerplants is described whereby the blades are placed in containers that move along a planetary path in a <span class="hlt">hardening</span> medium consisting of steel balls. The extent of surface <span class="hlt">hardening</span>, surface roughness, and residual stresses are determined for specimens of U8A steel and blades of EP718VD alloy treated under different conditions. The efficiency of the treatment in terms of increased blade durability and productivity is estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080014189','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080014189"><span>Non Radiation <span class="hlt">Hardened</span> Microprocessors in Spaced Based Remote Sensing Systems</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Decoursey, Robert J.; Estes, Robert F.; Melton, Ryan</p> <p>2006-01-01</p> <p>The CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) mission is a comprehensive suite of active and passive sensors including a 20Hz 230mj Nd:YAG lidar, a visible wavelength Earth-looking camera and an imaging infrared radiometer. CALIPSO flies in formation with the Earth Observing System Post-Meridian (EOS PM) train, provides continuous, near-simultaneous measurements and is a planned 3 year mission. CALIPSO was launched into a 98 degree sun synchronous Earth orbit in April of 2006 to study clouds and aerosols and acquires over 5 gigabytes of data every 24 hours. The ground track of one CALIPSO orbit as well as high and low intensity South Atlantic Anomaly outlines is shown. CALIPSO passes through the SAA several times each day. Spaced based remote sensing systems that include multiple instruments and/or instruments such as lidar generate large volumes of data and require robust real-time hardware and software mechanisms and high throughput processors. Due to onboard storage restrictions and telemetry downlink limitations these systems must pre-process and reduce the data before sending it to the ground. This onboard processing and realtime requirement load may mean that newer more powerful processors are needed even though acceptable radiation-<span class="hlt">hardened</span> versions have not yet been released. CALIPSO's single board computer payload controller processor is actually a set of four (4) voting non-radiation <span class="hlt">hardened</span> COTS Power PC 603r's built on a single width VME card by General Dynamics Advanced Information Systems (GDAIS). Significant radiation concerns for CALIPSO and other Low Earth Orbit (LEO) satellites include the South Atlantic Anomaly (SAA), the north and south poles and strong solar events. Over much of South America and extending into the South Atlantic Ocean the Van Allen radiation belts dip to just 200-800km and spacecraft entering this area are subjected to high energy protons and experience higher than normal Single Event Upset</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003E%26PSL.215..249K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003E%26PSL.215..249K"><span>Biotic effects of impacts and <span class="hlt">volcanism</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keller, Gerta</p> <p>2003-10-01</p> <p>The biotic effects of late Maastrichtian mantle plume <span class="hlt">volcanism</span> on Ninetyeast Ridge and Deccan <span class="hlt">volcanism</span> mirror those of the Cretaceous-Tertiary (KT) mass extinction and impact event. Planktonic foraminifera responded to high stress conditions with the same impoverished and small-sized species assemblages dominated by the disaster/opportunists Guembelitria cretacea, which characterize the KT mass extinction worldwide. Similar high stress late Maastrichtian assemblages have recently been documented from Madagascar, Israel and Egypt. Biotic effects of <span class="hlt">volcanism</span> cannot be differentiated from those of impacts, though every period of intense <span class="hlt">volcanism</span> is associated with high stress assemblages, this is not the case with every impact. The most catastrophic biotic effects occurred at the KT boundary (65.0 Ma) when intense Deccan <span class="hlt">volcanism</span> coincided with a major impact and caused the mass extinction of all tropical and subtropical species. The Chicxulub impact, which now appears to have predated the KT boundary by about 300 kyr, coincided with intense Deccan <span class="hlt">volcanism</span> that resulted in high biotic stress and greenhouse warming, but no major extinctions. The unequivocal connection between intense <span class="hlt">volcanism</span> and high stress assemblages during the late Maastrichtian to early Danian, and the evidence of multiple impacts, necessitates revision of current impact and mass extinction theories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GeoRL..3921809M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeoRL..3921809M"><span>First satellite identification of <span class="hlt">volcanic</span> carbon monoxide</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martínez-Alonso, Sara; Deeter, Merritt N.; Worden, Helen M.; Clerbaux, Cathy; Mao, Debbie; Gille, John C.</p> <p>2012-11-01</p> <p><span class="hlt">Volcanic</span> degassing produces abundant H2O and CO2, as well as SO2, HCl, H2S, S2, H2, HF, CO, and SiF4. <span class="hlt">Volcanic</span> SO2, HCl, and H2S have been detected from satellites in the past; the remaining species are analyzed in situ or using airborne instruments, with all the consequent limitations in safety and sampling, and at elevated costs. We report identification of high CO concentrations consistent with a <span class="hlt">volcanic</span> origin (the 2010 Eyjafjallajökull and 2011 Grímsvötn eruptions in Iceland) in data from the Measurements of Pollution in the Troposphere instrument (MOPITT) onboard EOS/Terra. The high CO values coincide spatially and temporally with ash plumes emanating from the eruptive centers, with elevated SO2 and aerosol optical thickness, as well as with high CO values in data from the Infrared Atmospheric Sounding Interferometer (IASI), onboard MetOp-A. CO has a positive indirect radiative forcing; climate models currently do not account for <span class="hlt">volcanic</span> CO emissions. Given global <span class="hlt">volcanic</span> CO2 emissions between 130 and 440 Tg/year and <span class="hlt">volcanic</span> CO:CO2 ratios from the literature, we estimate that average global <span class="hlt">volcanic</span> CO emissions may be on the order of ∼5.5 Tg/year, equivalent to the CO emissions caused by combined fossil fuel and biofuel combustion in Australia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6997877','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6997877"><span>Explosive <span class="hlt">volcanism</span>: Inception, evolution, and hazards</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1984-01-01</p> <p>One purpose of the studies is to provide assessments from the scientific community to aid policymakers in decisions on societal problems that involve geophysics. An important part of such an assessment is an evaluation of the adequacy of present geophysical knowledge and the appropriateness of present research programs to provide information required for those decisions. Some of the studies place more emphasis on assessing the present status of a field of geophysics and identifying the most promising directions for future research. This study on explosive <span class="hlt">volcanism</span> was begun soon after the cataclysmic eruptions of Mount St. Helens. It readily became apparent to the committee that an assessment of the explosive nature of volcanoes must cover all types of <span class="hlt">volcanic</span> activity; any volcano can be explosive. Improved understanding of the physics of <span class="hlt">volcanic</span> eruptions is an exciting goal that is vital to progress in hazard evaluation. The study of explosive <span class="hlt">volcanism</span> must include an appreciation of the severe social problems that are caused by erupting volcanoes. None is of greater urgency than planning for a crisis. This report considers the progress in research on these aspects of explosive <span class="hlt">volcanism</span> and the need for additional research efforts. This volume contains 13 papers. Topics include tectonism, <span class="hlt">volcanism</span>, <span class="hlt">volcanic</span> periodicity, eruptive mechanics, emergency planning and recommendations. Individual papers are indexed separately on the energy data base.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..DFD.AS009P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..DFD.AS009P"><span>Attracting structures in <span class="hlt">volcanic</span> ash transport</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peng, Jifeng</p> <p>2009-11-01</p> <p><span class="hlt">Volcanic</span> eruptions and ash clouds are a natural hazard that poses direct threats to aviation safety. They may also affect human and ecosystem health. Many transport and dispersion models have been developed to forecast trajectories of <span class="hlt">volcanic</span> ash clouds, as well as to plan safety measures. Predictions based on these models are heavily dependent on initial parameters of ash clouds, e.g., location, height, particle size and density distribution, water vs. ash content, etc. However, these initial parameters are usually difficult to determine, leading to possible inaccurate predictions of ash clouds trajectories. In this study, a dynamical systems approach is combined with <span class="hlt">volcanic</span> ash transport models to help improve prediction. A type of attracting structures in <span class="hlt">volcanic</span> ash transport is identified. These structures act as attractors in <span class="hlt">volcanic</span> ash transport, and they are independent of initial parameters of specific <span class="hlt">volcanic</span> eruptions. The attracting structures are associated with hazard zones with high concentrations of <span class="hlt">volcanic</span> ash. And the prediction in hazard maps can be used to plan flight route diversions and ground evacuations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.V31A1957P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.V31A1957P"><span>Attracting structures in <span class="hlt">volcanic</span> ash transport</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peng, J.; Peterson, R.</p> <p>2009-12-01</p> <p><span class="hlt">Volcanic</span> eruptions and ash clouds are a natural hazard that poses direct threats to aviation safety. They may also affect human and ecosystem health. Many transport and dispersion models have been developed to forecast trajectories of <span class="hlt">volcanic</span> ash clouds, as well as to plan safety measures. Predictions based on these models are heavily dependent on initial parameters of ash clouds, e.g., location, height, particle size and density distribution, water vs. ash content, etc. However, these initial parameters are usually difficult to determine, leading to possible inaccurate predictions of ash clouds trajectories. In this study, a dynamical systems approach is combined with <span class="hlt">volcanic</span> ash transport models to help improve prediction. A type of attracting structures in <span class="hlt">volcanic</span> ash transport is identified. These structures act as attractors in <span class="hlt">volcanic</span> ash transport, and are largely independent of initial parameters of specific <span class="hlt">volcanic</span> eruptions. The attracting structures are associated with hazard zones with high concentrations of <span class="hlt">volcanic</span> ash. The prediction in hazard maps can be used to plan flight route diversions and ground evacuations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..324..156L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..324..156L"><span>Evidence of recent deep magmatic activity at Cerro Bravo-Cerro Machín <span class="hlt">volcanic</span> complex, central Colombia. Implications for future <span class="hlt">volcanic</span> activity at Nevado del Ruiz, Cerro Machín and other volcanoes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Londono, John Makario</p> <p>2016-09-01</p> <p>In the last nine years (2007-2015), the Cerro Bravo-Cerro Machín <span class="hlt">volcanic</span> complex (CBCMVC), located in central Colombia, has experienced many changes in <span class="hlt">volcanic</span> activity. In particular at Nevado del Ruiz volcano (NRV), Cerro Machin volcano (CMV) and Cerro Bravo (CBV) volcano. The recent activity of NRV, as well as increasing seismic activity at other <span class="hlt">volcanic</span> centers of the CBCMVC, were preceded by notable changes in various geophysical and geochemical parameters, that suggests renewed magmatic activity is occurring at the <span class="hlt">volcanic</span> complex. The onset of this activity started with seismicity located west of the <span class="hlt">volcanic</span> complex, followed by seismicity at CBV and CMV. Later in 2010, strong seismicity was observed at NRV, with two small eruptions in 2012. After that, seismicity has been observed intermittently at other <span class="hlt">volcanic</span> centers such as Santa Isabel, Cerro España, Paramillo de Santa Rosa, Quindío and Tolima volcanoes, which persists until today. Local deformation was observed from 2007 at NRV, followed by possible regional deformation at various <span class="hlt">volcanic</span> centers between 2011 and 2013. In 2008, an increase in CO2 and Radon in <span class="hlt">soil</span> was observed at CBV, followed by a change in helium isotopes at CMV between 2009 and 2011. Moreover, SO2 showed an increase from 2010 at NRV, with values remaining high until the present. These observations suggest that renewed magmatic activity is currently occurring at CBCMVC. NRV shows changes in its activity that may be related to this new magmatic activity. NRV is currently exhibiting the most activity of any volcano in the CBCMVC, which may be due to it being the only open <span class="hlt">volcanic</span> system at this time. This suggests that over the coming years, there is a high probability of new unrest or an increase in <span class="hlt">volcanic</span> activity of other volcanoes of the CBCMVC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004SPIE.5441..227A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004SPIE.5441..227A"><span>NINJA: a noninvasive framework for internal computer security <span class="hlt">hardening</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Allen, Thomas G.; Thomson, Steve</p> <p>2004-07-01</p> <p>Vulnerabilities are a growing problem in both the commercial and government sector. The latest vulnerability information compiled by CERT/CC, for the year ending Dec. 31, 2002 reported 4129 vulnerabilities representing a 100% increase over the 2001 [1] (the 2003 report has not been published at the time of this writing). It doesn"t take long to realize that the growth rate of vulnerabilities greatly exceeds the rate at which the vulnerabilities can be fixed. It also doesn"t take long to realize that our nation"s networks are growing less secure at an accelerating rate. As organizations become aware of vulnerabilities they may initiate efforts to resolve them, but quickly realize that the size of the remediation project is greater than their current resources can handle. In addition, many IT tools that suggest solutions to the problems in reality only address "some" of the vulnerabilities leaving the organization unsecured and back to square one in searching for solutions. This paper proposes an auditing framework called NINJA (acronym for Network Investigation Notification Joint Architecture) for noninvasive daily scanning/auditing based on common security vulnerabilities that repeatedly occur in a network environment. This framework is used for performing regular audits in order to <span class="hlt">harden</span> an organizations security infrastructure. The framework is based on the results obtained by the Network Security Assessment Team (NSAT) which emulates adversarial computer network operations for US Air Force organizations. Auditing is the most time consuming factor involved in securing an organization's network infrastructure. The framework discussed in this paper uses existing scripting technologies to maintain a security <span class="hlt">hardened</span> system at a defined level of performance as specified by the computer security audit team. Mobile agents which were under development at the time of this writing are used at a minimum to improve the noninvasiveness of our scans. In general, noninvasive</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20120010625&hterms=geofisica&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgeofisica','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20120010625&hterms=geofisica&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgeofisica"><span>MISR Observations of Etna <span class="hlt">Volcanic</span> Plumes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scollo, S.; Kahn, R. A.; Nelson, D. L.; Coltelli, M.; Diner, D. J.; Garay, M. J.; Realmuto, V. J.</p> <p>2012-01-01</p> <p>In the last twelve years, Mt. Etna, located in eastern Sicily, has produced a great number of explosive eruptions. <span class="hlt">Volcanic</span> plumes have risen to several km above sea level and created problems for aviation and the communities living near the volcano. A reduction of hazards may be accomplished using remote sensing techniques to evaluate important features of <span class="hlt">volcanic</span> plumes. Since 2000, the Multiangle Imaging SpectroRadiometer (MISR) on board NASA s Terra spacecraft has been extensively used to study aerosol dispersal and to extract the three-dimensional structure of plumes coming from anthropogenic or natural sources, including volcanoes. In the present work, MISR data from several explosive events occurring at Etna are analyzed using a program named MINX (MISR INteractive eXplorer). MINX uses stereo matching techniques to evaluate the height of the <span class="hlt">volcanic</span> aerosol with a precision of a few hundred meters, and extracts aerosol properties from the MISR Standard products. We analyzed twenty <span class="hlt">volcanic</span> plumes produced during the 2000, 2001, 2002-03, 2006 and 2008 Etna eruptions, finding that <span class="hlt">volcanic</span> aerosol dispersal and column height obtained by this analysis is in good agreement with ground-based observations. MISR aerosol type retrievals: (1) clearly distinguish <span class="hlt">volcanic</span> plumes that are sulphate and/or water vapor dominated from ash-dominated ones; (2) detect even low concentrations of <span class="hlt">volcanic</span> ash in the atmosphere; (3) demonstrate that sulphate and/or water vapor dominated plumes consist of smaller-sized particles compared to ash plumes. This work highlights the potential of MISR to detect important <span class="hlt">volcanic</span> plume characteristics that can be used to constrain the eruption source parameters in <span class="hlt">volcanic</span> ash dispersion models. Further, the possibility of discriminating sulphate and/or water vapor dominated plumes from ash-dominated ones is important to better understand the atmospheric impact of these plumes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRD..11912660M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRD..11912660M"><span><span class="hlt">Volcanic</span> sulfate aerosol formation in the troposphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Erwan; Bekki, Slimane; Ninin, Charlotte; Bindeman, Ilya</p> <p>2014-11-01</p> <p>The isotopic composition of <span class="hlt">volcanic</span> sulfate provides insights into the atmospheric chemical processing of <span class="hlt">volcanic</span> plumes. First, mass-independent isotopic anomalies quantified by Δ17O and to a lesser extent Δ33S and Δ36S in sulfate depend on the relative importance of different oxidation mechanisms that generate sulfate aerosols. Second, the isotopic composition of sulfate (δ34S and δ18O) could be an indicator of fractionation (distillation/condensation) processes occurring in <span class="hlt">volcanic</span> plumes. Here we present analyses of O- and S isotopic compositions of <span class="hlt">volcanic</span> sulfate absorbed on very fresh <span class="hlt">volcanic</span> ash from nine moderate historical eruptions in the Northern Hemisphere. Most of our <span class="hlt">volcanic</span> sulfate samples, which are thought to have been generated in the troposphere or in the tropopause region, do not exhibit any significant mass-independent fractionation (MIF) isotopic anomalies, apart from those from an eruption of a Mexican volcano. Coupled to simple chemistry model calculations representative of the background atmosphere, our data set suggests that although H2O2 (a MIF-carrying oxidant) is thought to be by far the most efficient sulfur oxidant in the background atmosphere, it is probably quickly consumed in large dense tropospheric <span class="hlt">volcanic</span> plumes. We estimate that in the troposphere, at least, more than 90% of <span class="hlt">volcanic</span> secondary sulfate is not generated by MIF processes. <span class="hlt">Volcanic</span> S-bearing gases, mostly SO2, appear to be oxidized through channels that do not generate significant isotopically mass-independent sulfate, possibly via OH in the gas phase and/or transition metal ion catalysis in the aqueous phase. It is also likely that some of the sulfates sampled were not entirely produced by atmospheric oxidation processes but came out directly from volcanoes without any MIF anomalies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10105630','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10105630"><span>Influence of grain structure and solute composition on the work <span class="hlt">hardening</span> behavior of aluminium at cryogenic temperatures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chu, D.; Morris, J.W. Jr.</p> <p>1993-07-01</p> <p>An unrecrystallized structure is found to significantly improve the work <span class="hlt">hardening</span> characteristics by lowering the work <span class="hlt">hardening</span> rate during early stages of deformation. This is in contrast to a recrystallized structure, which requires a higher work <span class="hlt">hardening</span> rate to accommodate the greater degree of multiple slip necessary to maintain strain compatibility between the more randomly oriented grains. The stronger texture associated with the unrecrystallized structure allows deformation to occur more efficiently. Addition of magnesium also improves work <span class="hlt">hardening</span> by increasing overall level of the work <span class="hlt">hardening</span> rate. The improved characteristics of the work <span class="hlt">hardening</span> behavior result in a parallel increase in both the strength and ductility at cryogenic temperatures. These findings are positive since they suggest a method by which improvements in the work <span class="hlt">hardening</span> behavior and subsequent mechanical properties may be obtained through practical modifications of the microstructure and composition.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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