ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (2,693)
  • Other Sources
  • Wiley  (2,693)
  • AGU (American Geophysical Union)
  • 2010-2014  (2,693)
  • 1980-1984
  • 2011  (2,693)
  • Geophysical Research Letters  (1,141)
  • Journal of the American Ceramic Society  (772)
  • 4905
  • 6716
Collection
  • Articles  (2,693)
  • Other Sources
Source
Publisher
Years
  • 2010-2014  (2,693)
  • 1980-1984
Year
Journal
Topic
  • 1
    facet.materialart.
    Unknown
    The composition and structure of the Enceladus plume (2011)
    Wiley
    Details
    Publication Date: 2011-06-09
    Description: The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed an occultation of the Sun by the water vapor plume at the south polar region of Saturn's moon Enceladus. The Extreme Ultraviolet (EUV) spectrum is dominated by the spectral signature of H2O gas, with a nominal line-of-sight column density of 0.90 ± 0.23 × 1016 cm−2 (upper limit of 1.0 × 1016 cm−2). The upper limit for N2 is 5 × 1013 cm−2, or
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    What caused a recent increase in dust outbreaks over East Asia? (2011)
    Wiley
    Details
    Publication Date: 2011-06-10
    Description: A decadal change in the frequency of dust outbreaks for April over East Asia using World Meteorological Organization (WMO) synoptic data was identified. The causes of the decadal change can be defined in terms of aeolian erosivity (i.e., ability of wind to cause erosion represented by wind speed) and erodibility (i.e., susceptibility of soil and land surface to wind erosion represented by the threshold wind speed for dust outbreak). Dust outbreak frequency (fDO) increased at many stations in Mongolia, Inner Mongolia, northeastern China, and the Hexi Corridor from the 1990s to the 2000s. Especially, remarkable increases were observed for Mongolia. Strong wind frequency (fu〉ut5%) decreased or changed little over the period of study, and the 5th percentile of the threshold wind speed for dust outbreak (ut5%) decreased at many stations in Mongolia, eastern Inner Mongolia, and northeastern China. This suggests changes in erodibility factors increased fDO in these regions. There are stations where fu〉ut5% increased and ut5% remained relatively constant in western Inner Mongolia and the Hexi Corridor. This suggests changes in the erosivity factor increased fDO at these locations. The change in erodibility is linked, in part, to the effect of dead leaves of grasses in spring, which are the residue of vegetation in summer from the previous year, which can cause an increase in the threshold wind speed.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    The impact of Asian and non-Asian anthropogenic aerosols on 20th century Asian summer monsoon (2011)
    Wiley
    Details
    Publication Date: 2011-06-11
    Description: Studies into the impact of anthropogenic aerosols on regional summer monsoon rainfall have focused on a black carbon-induced enhancement and a sulfate-induced suppression. The latter encompasses significant Asian and non-Asian sources, but their relative roles in forcing historical global and regional monsoon trends are largely unexplored. Using targeted 20th century coupled climate simulations, designed to isolate the impact from anthropogenic aerosols, we show that Asian aerosols induce a weak suppression of global summer monsoon, confined to the East Asian region. The addition of non-Asian aerosols generates an enhancement and broadening of cooler temperatures over Europe and Asia relative to the ambient oceans, supporting stronger northerly flows that further suppress Asian monsoon rainfall. Furthermore, atmospheric convection is directed away from the Asian monsoon regions, resulting in an equatorward shift in rainfall. Our results highlight the importance of the non-Asian aerosols in exacerbating the impact of Asian aerosols on global monsoon rainfall, particularly across Asia.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Differences in future recharge estimates due to GCMs, downscaling methods and hydrological models (2011)
    Wiley
    Details
    Publication Date: 2011-06-14
    Description: The impact of climate change upon groundwater has an increasing profile in the literature but there is little guidance on selecting Global Climate Models (GCMs), downscaling methods or hydrological models. This paper quantifies the relative uncertainties inherent in projections of future recharge contributed by multiple GCMs, downscaling methods and hydrological models at three locations across southern Australia. Results highlight that the choice of GCM is the largest source of uncertainty, with a median range between the highest and lowest GCM of 53% of the historical recharge for a given downscaling method and hydrological model. The downscaling method is the next largest source of uncertainty with a median range of 44% and the choice of hydrological model is the source of the least uncertainty with a median range of 24%. These results strongly suggest that impact studies should use multiple GCMs and give careful consideration to the choice of downscaling methods.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    The Effect of Bi2O3/SiO2 Molar Ratio and Annealing on the dc Degradation of ZnO Varistors (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: The dc electrical stability of ZnO varistors was effectively improved by controlling the composition proportion of Bi 2 O 3 and SiO 2 as well as annealing condition. The microstructure, current–voltage ( I – V ) property, and dc degradation characteristics are significantly affected by the molar ratio of Bi 2 O 3 to SiO 2 in composition. It is found that a phase transition from β-Bi 2 O 3 (with dissolved Si) to Bi 12 SiO 20 , with a volume contraction of 5.88%, occurred after annealing at 850°C. The formed Bi 12 SiO 20 plays an important role in improving the electrical stability by inhibiting the oxygen-desorption at the grain boundary.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Drivers of past and future Southern Ocean change: Stratospheric ozone versus greenhouse gas impacts (2011)
    Wiley
    Details
    Publication Date: 2011-06-16
    Description: We study the separate impacts of changing atmospheric greenhouse gas (GHG) and stratospheric ozone concentrations on past (1960–2010) and future (2010–2100) Southern Ocean conditions. To this end we employ a coupled atmosphere-ocean model with interactive stratospheric chemistry. In our model we separately prescribe i) GHGs that monotonically increase to 2100 and ii) ozone depleting substances (ODSs) that rapidly increase to a maximum in 1995 and then slowly return to 1960 values around 2100, following moderate emission scenarios. Past GHG and ODS changes in our model drive, in about equal measure in the annual mean, poleward intensified surface winds which act to strengthen the sub polar meridional ocean circulation cell and Antarctic Circumpolar Current (ACC). Future GHG-induced oceanic changes continue nearly monotonically to 2100, while the ODS-induced ACC transport peaks, and then reverses, a couple of decades after the ODS maximum in 1995. The ODS impact on ACC transport exceeds the corresponding GHG impact up to the second quarter of the 21st century, a result that highlights the importance of often-neglected stratospheric ozone trends for the simulation of the ocean circulation.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Ferroelectric-to-Relaxor Crossover in (1-x)BaTiO3-xBiYbO3 (0 ≤ x ≤ 0.08) Ceramics (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Dense (1- x )BaTiO 3 - x BiYbO 3 (BBTYb) ceramics were fabricated by the solid state reaction method. According to X-ray diffraction data, the average crystal symmetry of x ≤ 0.04 ceramics is described by the non-centro symmetric tetragonal P 4 mm space group, whereas the average crystal symmetry of x ≥ 0.06 ceramics is better described by the centrosymmetric cubic Pm m space group. Raman spectroscopy supports a change in the average crystal symmetry at x ≥ 0.06, but also reveals differences in the local crystal structure for x ≤ 0.04. In this compositional range, BBTYb ceramics undergo a so-called ferroelectric-to-relaxor crossover, which is a manifestation of the continuous modification of local structure. Weak-relaxor behavior was observed in x ≥ 0.06 ceramics, for which the local crystal symmetry departs from cubic, as indicated by the presence of Raman spectra.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Mass balance of Greenland's three largest outlet glaciers, 2000–2010 (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Acceleration of Greenland's three largest outlet glaciers, Helheim, Kangerdlugssuaq and Jakobshavn Isbræ, accounted for a substantial portion of the ice sheet's mass loss over the past decade. Rapid changes in their discharge, however, make their cumulative mass-change uncertain. We derive monthly mass balance rates and cumulative balance from discharge and surface mass balance (SMB) rates for these glaciers from 2000 through 2010. Despite the dramatic changes observed at Helheim, the glacier gained mass over the period, due primarily to the short-duration of acceleration and a likely longer-term positive balance. In contrast, Jakobshavn Isbræ lost an equivalent of over 11 times the average annual SMB and loss continues to accelerate. Kangerdlugssuaq lost over 7 times its annual average SMB, but loss has returned to the 2000 rate. These differences point to contrasts in the long-term evolution of these glaciers and the danger in basing predictions on extrapolations of recent changes.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Contribution of Pacific wind stress to multi-decadal variations in upper-ocean heat content and sea level in the tropical south Indian Ocean (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Reconstructions of the spatial pattern of recent multi-decadal sea level trends in the Indian Ocean (IO) indicate a zonally-extended band in the southern tropics where sea level has substantially fallen between the 1960s and 1990s; the decline is consistent with the observed subsurface cooling associated with a shoaling thermocline in this region. Here the origin and spatio-temporal characteristics of these trends are elucidated by a sequence of ocean model simulations. Whereas interannual variability in the southwestern tropical IO appears mainly governed by IO atmospheric forcing, longer term changes in the south tropical IO involve a strong contribution from the western Pacific via wave transmission of thermocline anomalies through the Indonesian Archipelago, and their subsequent westward propagation by baroclinic Rossby waves. The late 20th-century IO subsurface cooling trend reversed in the 1990s, reflecting the major regime shift in the tropical Pacific easterlies associated with the Pacific Decadal Oscillation.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Rare earth (RE)-doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of postceramming. The main characteristics of the RE-doped oxide nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline-earth element used as phase-separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However, in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporating new doped materials to realize active optical fibers for constructing lasers and amplifiers.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 11
    facet.materialart.
    Unknown
    Preparation of Crystal-Axis-Oriented Barium Calcium Titanate Plate-Like Particles and Its Application to Oriented Ceramic (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: A novel two-step process has been developed for the preparation of Ba 0.9 Ca 0.1 TiO 3 plate-like grains with [110]-crystal-axis-orientation. In the first step, plate-like particles of a layered titanate H 1.07 Ti 1.73 O 4 are solvothermally treated in a Ba(OH) 2 –Ca(OH) 2 mixed solution, and then in the second step, heat-treat the solvothermally treated sample to complete the formation reaction of Ba 0.9 Ca 0.1 TiO 3 . The formation reaction and nanostructure of the Ba 0.9 Ca 0.1 TiO 3 plate-like grains were characterized using X-ray diffraction, FE-SEM, TEM, and SEAD. The Ba 0.9 Ca 0.1 TiO 3 plate-like grains are constructed from spherical nanoparticles with particle size of about 10–20 nm. The spherical nanocrystals in each plate-like grain arrange in the same crystal-axis-orientation direction, which presented a diffraction pattern similar to the single crystal. The Ba 0.9 Ca 0.1 TiO 3 plate-like grains were utilized to fabricate an oriented Ba 0.9 Ca 0.1 TiO 3 ceramic to demonstrate the potential application of the plate-like grains, and the [110]-oriented Ba 0.9 Ca 0.1 TiO 3 ceramic with a high degree orientation of F 110 = 76% and small grain size of about 1–2 μm was obtained.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 12
    facet.materialart.
    Unknown
    Nanoceria – Energetics of Surfaces, Interfaces and Water Adsorption (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: The surface and interface enthalpies of CeO 2 were studied by high temperature oxide melt solution calorimetry combined with water adsorption calorimetry. The surface enthalpies of the hydrated and anhydrous surfaces are 0.86 ± 0.02 and 1.16 ± 0.02 J/m 2 , respectively. The water adsorption enthalpies are similar for nano and bulk ceria; for the nano ceria the integral adsorption enthalpy for chemisorbed water relative to water vapor is −59.82 ± 0.74 kJ/mol with coverage of 8.79 ± 0.39 H 2 O/nm 2 and for the bulk it is −61.69 ± 1.26 kJ/mol with coverage of 8.15 ± 0.66 H 2 O/nm 2 . The interfacial enthalpy is 0.81 ± 0.14 J/m 2 . The obtained energies are in good agreement with reported data from atomistic simulations and less direct experimental determinations.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 13
    facet.materialart.
    Unknown
    Statistical Evaluation of Fatigue Crack Propagation from Natural Flaws in Silicon Nitride (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Silicon nitride exhibits fatigue based on cyclic crack propagation which is critical for components under repeated loading. Lifetime predictions for such components are usually based on power law formulations and are most sensitive to the crack growth exponent n . Various statistical procedures exist to determine the parameters from cyclic tests of un-cracked smooth samples. In this work, an analysis is presented for silicon nitride (SL200) lifetime data with a focus on the relation between load ratio and the exponent n . It is found that n increases with the load ratio which has also been observed for macroscopic cracks in silicon nitride earlier. A high degree of uncertainty is associated with the crack growth exponent due to the sparse lifetime database. A pooling strategy is presented which increases the sample size of the underlying lifetime distribution and successfully decreases the scatter in the crack propagation curves and the uncertainty in the crack propagation exponent and, thus, in the lifetime prediction.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 14
    facet.materialart.
    Unknown
    HF-driven currents in the polar ionosphere (2011)
    Wiley
    Details
    Publication Date: 2011-06-21
    Description: Polar ionospheric heaters have generated ULF/ELF/VLF waves by modulating the auroral electrojet at D/E region altitudes. We present theoretical/computational results indicating that modulated F-region HF heating can generate ionospheric currents even in the absence of electrojet currents. The ELF currents are driven in a two-step process. First, the pressure gradient associated with F-region electron heating drives a local diamagnetic current. This acts as an antenna to inject Magneto-Sonic (MS) waves in the ionospheric plasma. Second, the electric field of the magneto-sonic wave drives Hall currents when it reaches the E region of the ionosphere. The Hall currents act as a secondary antenna that injects waves in the Earth-Ionosphere Waveguide below and Shear Alfven waves upwards to the conjugate regions. The paper examines the scaling and limitations of the concept and suggests proof-of-principle experiments using the HAARP ionospheric heater.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 15
    facet.materialart.
    Unknown
    Strong thermospheric cooling during the 2009 major stratosphere warming (2011)
    Wiley
    Details
    Publication Date: 2011-06-21
    Description: Thermospheric density simultaneously observed by the CHAMP and GRACE satellites in both the pre-dawn and afternoon local time sectors undergoes significant decrease across both hemispheres during the major stratospheric sudden warming (SSW) in January 2009. This decrease is largest in the equatorial region near the subsolar latitude, reaching ∼30% at 325 km, and 45% at 475 km altitude in the afternoon sector. This large density drop demonstrates a substantial cooling of about 50 Kelvin in the equatorial upper thermosphere. Furthermore, the cooling varies clearly with longitude in terms of magnitude and the timing of the maximum cooling. Thermosphere cooling can have important impact on the ionosphere, as indicated by simultaneous plasma observations. Though many questions remain about what causes the cooling, our results open a new perspective for investigating the global coupling of the lower and upper atmosphere during SSWs.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 16
    facet.materialart.
    Unknown
    A Rapid-Doping Method for High-Throughput Discovery Applied to Thick-Film PTCR Materials (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: A novel high-throughput combinatorial library preparation technique for ceramics requiring low levels of dopant is demonstrated and assessed for the case of donor-doped barium titanate (BT) materials with positive temperature coefficient of resistance (PTCR). The droplet-doping process is performed by infiltrating liquid dopant precursors into porous BT disks and viewed using a high-speed camera. The resulting dopant distribution in the body of the disk shows high uniformity as assessed by energy dispersive (EDS) and wavelength dispersive (WDS) spectroscopies. X-ray diffraction (XRD) measurements and resistivity–temperature (ρ– T ) curves show evidence of the changes in structure and PTCR profiles with change in composition and are closely matched to previously published data for samples made by conventional ceramic routes. The procedure, thus validated, has the potential to deliver dopant-doped BT-based PTCR libraries rapidly with a very wide range of dopant mixtures and concentrations for electrical property measurement and deserves to be applied to other low-level dopant ceramic systems.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 17
    facet.materialart.
    Unknown
    The drought of 2010 in the context of historical droughts in the Amazon region (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: The year 2010 featured a widespread drought in the Amazon rain forest, which was more severe than the “once-in-a-century” drought of 2005. Water levels of major Amazon tributaries fell drastically to unprecedented low values, and isolated the floodplain population whose transportation depends upon on local streams which completely dried up. The drought of 2010 in Amazonia started in early austral summer during El Niño and then was intensified as a consequence of the warming of the tropical North Atlantic. An observed tendency for an increase in dry and very dry events, particularly in southern Amazonia during the dry season, is concomitant with an increase in the length of the dry season. Our results suggest that it is by means of a longer dry season that warming in the tropical North Atlantic affects the hydrology of the Amazon Rivers at the end of the recession period (austral spring). This process is, sometimes, further aggravated by deficient rainfall in the previous wet season.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 18
    facet.materialart.
    Unknown
    Influence of subtropical and polar sea-surface temperature anomalies on temperatures in Eurasia (2011)
    Wiley
    Details
    Publication Date: 2011-06-23
    Description: In summer 2010 an exceptional heatwave occurred over western Russia. At the same time sea-surface temperatures (SSTs) were anomalously warm in the Barents Sea and the Arabian Sea. We investigate a possible link between these two SST anomalies by prescribing SST anomalies separately and combined in an ensemble of climate model simulations. The positive surface air temperature response over western Russia is strengthened if both SST forcings are combined. While the SST anomalies in the Arabian Sea are likely due to natural variability the sea surface in the Barents Sea is expected to warm in future and the sea-ice cover to decline enhancing the warming. Thus, we hypothesize that heatwaves over Europe and Russia will likely become more frequent as a result of the dynamic response of the atmosphere in addition to what is expected from the change in mean temperature.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 19
    facet.materialart.
    Unknown
    Influence of non-Newtonian rheology on magma degassing (2011)
    Wiley
    Details
    Publication Date: 2011-06-24
    Description: Many volcanoes exhibit temporal changes in their degassing process, from rapid gas puffing to lava fountaining and long-lasting quiescent passive degassing periods. This range of behaviors has been explained in terms of changes in gas flux and/or magma input rate. We report here a simple laboratory experiment which shows that the non-Newtonian rheology of magma can be responsible, alone, for such intriguing behavior, even in a stationary gas flux regime. We inject a constant gas flow-rate Q at the bottom of a non-Newtonian fluid column, and demonstrate the existence of a critical flow rate Q* above which the system spontaneously alternates between a bubbling and a channeling regime, where a gas channel crosses the entire fluid column. The threshold Q* depends on the fluid rheological properties which are controlled, in particular, by the gas volume fraction (or void fraction) $\phi$. When $\phi$ increases, Q* decreases and the degassing regime changes. Non-Newtonian properties of magma might therefore play a crucial role in volcanic eruption dynamics.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 20
    facet.materialart.
    Unknown
    Micromechanics of asperity rupture during laboratory stick slip experiments (2011)
    Wiley
    Details
    Publication Date: 2011-06-28
    Description: Acoustic emissions and tremor-like signals are widely recorded in laboratory experiments. We are able to isolate the physical origins of these signals using high resolution nanoseismic analysis. The use of a picometer-sensitive, wide-band sensor array permits us to determine force-time functions and focal mechanisms for discrete events found amid the “noise” of friction, similar to how low frequency earthquakes are found buried within tremor. We interpret these localized events to be the rupture of μm-sized contacts, known as asperities. We performed stick-slip experiments on plastic/plastic and rock/rock interfaces and found a systematic difference between the nano earthquakes: the rock interface produces very rapid (
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 21
    facet.materialart.
    Unknown
    Arctic cyclogenesis at the marginal ice zone: A contributory mechanism for the temperature amplification? (2011)
    Wiley
    Details
    Publication Date: 2011-06-28
    Description: Rapid sea-ice retreat over the Arctic Ocean has a leading role in Arctic amplification. The sea-ice extent dramatically recovers during every freezing season, so despite the recent summer sea-ice retreat, there must be extraordinary heat exchange between the lower atmosphere and upper ocean. However, the underlying mechanisms for this remain uncertain. Here we show that autumn frontal cyclogenesis is a crucial event in the Arctic air-sea coupled system. Our shipboard Doppler radar and intensive radiosonde observations at the marginal ice zone detected an explosive frontal cyclogenesis, with coupling between upper and lower tropospheric vortices. The thermal contrast between ocean and ice surfaces is likely favorable to cyclogenesis with an identical life-cycle to that at mid-latitudes. This suggests a northward shift of meridional heat transport. The 1.5 K temperature decrease in the upper ocean after the cold front has passed reveals that a large amount of heat is transported into the atmosphere. This is an invaluable example of the fact that sea ice retreat contributes to polar amplification of surface air temperature increase.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 22
    facet.materialart.
    Unknown
    Influences of Target and Liquid Media on Morphologies and Optical Properties of ZnO Nanoparticles Prepared by Laser Ablation in Solution (2011)
    Wiley
    Details
    Publication Date: 2011-06-08
    Description: This article reports the target and liquid media influences on the microstructures and optical properties of ZnO nanoparticles synthesized using pulsed laser ablation (PLA) method. Zinc and ZnO target were ablated with laser in pure water and surfactant solution, respectively. The obtained nanoparticles were characterized using X-ray diffraction spectrometer, transmission electron microscopy, X-ray photoelectron spectroscopy, optical absorption spectrum, and photoluminescence spectrum. The nanoparticles synthesized in surfactant solution were of spherical shapes, but with different microstructures and optical properties. The nanoparticles synthesized in water using zinc target showed rod shapes and both UV and visible emissions. When ZnO target was ablated in water, flake-shaped nanoparticles were synthesized and strong UV, but weak violet emissions were observed. At last, the influences of PLA growth condition on the nanoparticles microstructures and the relationship between the optical properties and their stoichiometries were discussed.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 23
    facet.materialart.
    Unknown
    B-site Dopant Effect on the Thermal Expansion in the (1-x)PbTiO3-xBiMeO3 Solid Solution (Me = Fe, In, Sc) (2011)
    Wiley
    Details
    Publication Date: 2011-06-08
    Description: The (1- x )PbTiO 3 - x BiMeO 3 (Me = Fe, In, Sc) solid solutions were prepared and investigated using high-temperature X-ray diffraction for the B-site dopant effect on their thermal expansion behaviors. Compared with PbTiO 3 , the negative thermal expansion of (1- x )PbTiO 3 - x BiFeO 3 was enhanced, whereas that of (1- x )PbTiO 3 - x BiInO 3 was a little weakened and was much weakened in (1- x )PbTiO 3 - x BiScO 3 . An empirical linear correlation between the average effective radius of the B-site cations and the unit cell volumes at Curie point of the solid solutions was concluded. The relationship was also observed in other PbTiO 3 -BiMeO 3 -type solid solutions and was supposed to be widely useful in predicting the thermal expansion coefficient of compounds of this sort. Above the Curie point, the unit cell volumes of the compounds were determined by the radii of the doped B-site cations. The weaking and vanishing of the lattice distortion caused by spontaneous polarization displacements was proved by Raman scatting spectrum, which supported the relationship in the lattice dynamic aspect.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 24
    facet.materialart.
    Unknown
    Preparation of SiCN(O) Material with Vinyl Trichlorosilane (2011)
    Wiley
    Details
    Publication Date: 2011-06-08
    Description: A new route to synthesize SiCN(O) precursor is adopted with vinyl trichlorosilane and solid ammonia carbamate as starting materials. The reaction is controlled in autoclave. A mixture of solid oxygen-rich polysilazane and ammonia chloride is obtained for the reason of dimensional poly-condensation. It is adopted to take the byproduct apart using chemical vapor transportation. The mixture is pyrolyzed at 1100°C for 2 h in Ar, and black SiCN(O) powder is separated from the byproduct. The chemical component of the powder is Si 1.00 C 2.07 N 1.09 O 0.29 . XRD analysis indicates that the black powder keeps amorphous at a temperature up to 1450°C. At 1500°C, SiC phase is first precipitated. With the temperature further increased, Si 2 N 2 O phase appeared. It provides a way to separate other nitrides from ammonia chloride in similar system.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 25
    facet.materialart.
    Unknown
    Preparation of Nano Alumina Powder via Combustion Synthesis: Porous Structure Optimization via Taguchi L16 Design (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Nano alumina powders have been synthesized by combustion method using eight new fuels. The effectiveness of key process factors on the production of nanoparticles was investigated and optimized using Taguchi L 16 array design. The products were characterized by XRD, BET, TGA, EDX, FESEM, and TEM analyses. Results demonstrated that the nano-structured aluminum oxide powders had crystal sizes between 7.2 and 13 nm and specific surface areas between 21.0 and 70.0 m 2 /g. The synthesis of γ-alumina was modified to achieve higher specific surface area (122.6 m 2 /g). A nano-network of powders which was woven by alumina nano-fibers was successfully fabricated by the modification route. The length and diameter of fibers were about 160 and 10 nm, respectively.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 26
    facet.materialart.
    Unknown
    Aqueous Tape Casting Using Organic Binder: A Case Study with YSZ (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Aqueous tape casting of yttria stabilized zirconia (YSZ) having very wide particle size range was investigated using bio-polymer, gelatin as binder and glycerol as plasticizer. Best dispersion of YSZ powder was obtained by using an anionic polyelectrolyte DARVAN 821A at pH 7.5. Gelling properties of gelatin, plasticized with water and glycerol have been studied by dynamic shear measurements. Decreasing concentration of gelatin significantly decreases the gelling temperature of it. With the addition of optimum amount of binder and plasticizer, it has been possible to prepare stable YSZ suspension of 45–50 wt% solid loading that exhibited the desired shear-thinning behavior. Green tapes with good flexibility (strain to failure: 12%–24%) and strength (2–3 MPa) with total organics content of 10–14 wt% were obtained. After removal of organics, the tapes were sintered at 1550°C for 3 h. The sintered density of the tapes thus obtained was about 99% of the theoretical density. The grain size of the sintered tape was fairly large (10–20 μm); but the surface of the sintered tape (thickness: 100 μm) did not show any visible porosity.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 27
    facet.materialart.
    Unknown
    Phase Stability, Electronic Structure, Compressibility, Elastic and Optical Properties of a Newly Discovered Ti3SnC2: A First-Principle Study (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: The phase stability, electronic structure, compressibility, optical and elastic properties of two polymorphs of Ti 3 SnC 2 were investigated using first-principle calculation. α-Ti 3 SnC 2 is confirmed to be the preferred equilibrium phase under high pressure and high temperature. The electronic structure calculations reveal that the Ti and C atoms form a strong Ti1-C-Ti2-C-Ti1 covalent bond chain while the bonding between Ti1 and Sn is relatively weak. In the low frequency range from radio waves to visible light, Ti 3 SnC 2 behaves similarly with TiC. This material exhibits anisotropic compressibility under hydrostatic pressure: it is more compressible along the c -direction than along a -direction, related to the different bond stiffness and bond angle changes under high pressure. The second-order elastic coefficients were calculated. For the α-phase, the bulk, B , shear, G , and Young's moduli, E , are calculated to be 169.4, 124, and 197.4 GPa, respectively. The low G / B ratio partially explains why Ti 3 SnC 2 is relatively soft and damage tolerant.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 28
    facet.materialart.
    Unknown
    Global energy transfer during a magnetospheric field line resonance (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Field line resonances (FLRs) are important for transferring energy from fast mode waves to shear Alfvén waves in the Earth's magnetosphere. Using simultaneous multi-satellite observations from THEMIS and the IMAGE ground magnetometer array, we report on the transfer of energy from compressional magnetopause undulations through an FLR to the ionosphere. Energy diversion from the magnetosphere to the ionosphere took place at the FLR: we find net energy flux there to have comparable values in the radial and the field-aligned directions. The field-aligned energy flux, when mapped to the ionosphere, was 0.70 mW/m2 and consistent with the inferred Joule dissipation rate at that time. IMAGE's regional monitoring of wave activity reveals that the temporal evolution of the FLR wave power and energy transfer were correlated with the amplitude profile of magnetopause undulations, confirming these waves to be the FLR driver.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 29
    facet.materialart.
    Unknown
    Lightning development associated with two negative gigantic jets (2011)
    Wiley
    Details
    Publication Date: 2011-06-21
    Description: We report observations of two negative polarity gigantic jets sufficiently near very high-frequency (VHF) lightning mapping networks that the associated lightning characteristics and charge transfer could be investigated. In both cases the gigantic jet-producing flash began as ordinary intracloud lightning with upper level channels attempting to exit the cloud, and then produced the upward gigantic jet. Neither flash had developed channels to ground, confirming that the major charge transfer during gigantic jets occurred between the cloud and ionosphere. The leader progression of one event was detected at altitudes above 20 km, demonstrating the possibility of detecting and tracking the propagation of negative jets above the cloud with VHF techniques.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 30
    facet.materialart.
    Unknown
    The Effects of Residual Stress Distributions on Indentation-induced Microcracking in B4C–TiB2 Eutectic Ceramic Composites (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: The boron carbide (B 4 C) titanium diboride (TiB 2 ) ceramic eutectic is being investigated for armor and tribological applications. Electron diffraction shows [11 0] TiB 2 //[21 1] B 4 C//growth direction, (0001) TiB 2 //( 2 0) B 4 C is parallel to the interface plane, and transmission electron microscopy (TEM) imaging reveals no interface phase. Thermal residual stress distributions are calculated via finite element modeling of an experimental eutectic microstructure. The B 4 C matrix is found to be about 400 MPa in compression, and the TiB 2 lamellae approximately 1.3 GPa in tension. Stress and strain energy concentrations are found at the tips of TiB 2 lamellae. TEM of deformed materials correlates well with the finite element calculations, showing preferential fracture in areas of stress concentration. Interfacial delamination and crack deflection are also observed in deformed materials.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 31
    facet.materialart.
    Unknown
    Characteristics of the TIGGE multimodel ensemble prediction system in representing forecast variability associated with extratropical transition (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: The characteristics of the extratropical transition (ET) of tropical cyclones and its impact on the midlatitude flow are examined in the THORPEX Interactive Grand Global Ensemble (TIGGE) multimodel ensemble prediction system (EPS). Ten ensemble forecasts initialized prior to ET for five tropical cyclones in 2008 are investigated using an empirical orthogonal function analysis and fuzzy clustering methodology. Each forecast contains 231 members from eight different global EPS. The EPS contributing to TIGGE differ in their spread and their contributions to the different scenarios. Some of the individual EPS are generally confined to only a few scenarios, whereas others contribute regularly to almost all. TIGGE contains more development scenarios than European Centre for Medium Range Weather Forecast (ECMWF) EPS but the full range of development scenarios is only found with the ECMWF included in the multimodel EPS.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 32
    facet.materialart.
    Unknown
    The 3D model of the plasmasphere coupled to the ionosphere (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: The 3D dynamic model of the plasmasphere developed by Pierrard and Stegen (2008) has been coupled with the ionospheric IRI model. In addition to the electron number density, the plasmaspheric model is also developed to include the temperature profiles of the different particles and ion composition at altitudes from 60 to 2000 km. Results of the model for the F region trough are compared with coincident observations of middle and top ionosphere by means of satellite tomography and radar measurements. A good match between the model and observations supports the idea that the present model is useful for investigating physical mechanism involved in the plasmasphere-ionosphere coupling and for acquiring information about the plasmaspheric behaviour based on ionospheric observations.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 33
    facet.materialart.
    Unknown
    Transport and coastal zooplankton communities in the northern California Current system (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: Alongshore transport was estimated from the gridded AVISO altimeter data and water level data from NOAA tide gauges (1993–2010) for the northern California Current (NCC) system. The biomass of the cold neritic copepods including Calanus marshallae, Pseudocalanus mimus and Acartia longiremis (dominants in the eastern Bering Sea, coastal Gulf of Alaska, and NCC) was estimated from a 15 year time series of zooplankton samples (1996–2010) collected biweekly at a coastal station 9 km off Newport Oregon U.S.A. The alongshore currents and the biomass of the cold neritic copepods exhibit a strong seasonal pattern and fluctuate in opposite phase: positive alongshore current (from south) leads to low biomass in winter and negative alongshore current (from north) leads to high biomass in summer. When the Pacific Decadal Oscillation (PDO) is positive, i.e., warm conditions around the northeast Pacific, there is more movement of water from the south in the NCC during winter. When the PDO is negative, there is more movement of water from the north during summer. The mean biomass of cold neritic copepods was positively correlated with the survival rate of juvenile coho salmon and cumulative transport was negatively correlated with coho salmon survival, i.e., in years when a greater portion of the source waters feeding the NCC enters from the north, the greater the salmon survival. We conclude that alongshore transport manifests PDO signals and serves as a linkage between large scale forcing to local ecosystem dynamics.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 34
    facet.materialart.
    Unknown
    The average influence of decadal solar forcing on the atmosphere in the South Pacific region (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: Composite mean difference analyses are applied to historical sea level pressure (SLP) and sea surface temperature (SST) data to investigate the spatial dependence of the Pacific climate system response to 11-year solar forcing. Previous work has found that the SST and SLP responses are most clearly detected near the times of sunspot maxima, which occur as much as two years prior to the centers of the broad decadal solar cycle maxima. In January–February, the SLP response at sunspot maximum is nearly the same on either side of the equator, although the amplitude is larger in the winter hemisphere. The solar influence is seen as above normal SLP in the sub-Arctic Pacific, as found previously, and as corresponding positive SLP anomalies in the sub-Antarctic Pacific, as shown here for the first time. These SLP anomalies are associated with previously documented signals at sunspot maxima of greater ocean upwelling and cooling along the Pacific equator, and a poleward extension of the tropical convergence zones in both hemispheres. Previous studies using multiple linear regression methods show the broad decadal solar maxima being associated with the lagged warm response in equatorial Pacific SSTs seen in the composites, which is not inconsistent with the present results. In the South Pacific Ocean, the solar effect is visible in the southern summer in the year before the sunspot number peak. The SST and SLP anomalies in the South Pacific in the solar peaks differ markedly from those in Cold Events (La Niña events) of the Southern Oscillation.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 35
    facet.materialart.
    Unknown
    Lateral and Normal Forces in Polymer-Mediated Interaction of Alumina Surfaces (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: Polymer-mediated interaction forces between an α-alumina particle and c-sapphire surfaces in methylcellulose solutions were measured by the atomic force microscope colloid probe technique. The effect of water soluble methylcellulose on normal and lateral surface forces was probed to understand the binding action of methylcellulose polymers. Methylcellulose bridgings up to ~300 nm in length have been measured. However, pretreatment of surfaces with NH 4 + salt of poly(acrylic acid) resulted in fewer bridging events, probably due to preferential adsorption. The presence of methylcellulose bridging in friction loops was also measured in the form of superimposed spikes.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 36
    facet.materialart.
    Unknown
    Role of TiO2 Seed Layer Thickness on the Nanostructure Evolution and Phase Transformation Behavior of Sputtered PZT Thin Films During Post-Deposition Air-Annealing (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: An optimum TiO 2 seed layer is said to facilitate nucleation and subsequent growth of perovskite phase in Pb(Zr,Ti)O 3 (PZT) films during annealing. The actual causes that prevent perovskite growth, particularly in sputtered PZT films on thick TiO 2 seed layers are not yet understood clearly. Herein, based on the results of X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), and analytical scanning/transmission electron microscopy (S/TEM) with semi-quantitative elemental mapping using energy dispersive X-ray (EDX) spectrum imaging, the post-annealing crystallization trend of r.f. magnetron sputter-deposited amorphous PZT films has been scrutinized as a function of TiO 2 seed layer thickness. Upon annealing, PZT films on thin TiO 2 layers (~20–100 nm) partially crystallize into perovskite PZT via a transient pyrochlore/fluorite phase. However, no perovskite phase forms on thicker (~550 nm) TiO 2 layer. Thickness of underlying TiO 2 seed layer strongly influences the crystallization, phase formation, texture, and surface morphology of the PZT films. During crystallization, Pb diffuses away from the PZT film to form solid solution with TiO 2 seed layer. Perovskite PZT phase transformation requires a minimum Pb-concentration within the transient pyrochlore/fluorite phase. During the growth of perovskite grains, Zr gets segregated, resulting in Zr-concentration build-up within the surrounding disordered fcc fluorite phase.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 37
    facet.materialart.
    Unknown
    Energy Transfer Mechanism and Luminescence of Ce0.67Tb0.33Mg1-xMnxAl11O19 Wide-Color-Gamut CCFL Green Phosphor (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: Using a convenient solid-state reaction Ce 0.67 Tb 0.33 Mg 1- x Mn x Al 11 O 19 green phosphors were prepared. The effect of Mn 2+ doping on the luminescence properties, energy transfer mechanism, and color gamut under 254 nm excitation were investigated. The energy transfer from (Ce,Tb) 3+ to Mn 2+ was found to be due to multipolar interactions of the dipole–quadrupole mechanism from theoretical fitting results. The critical distance was calculated to be 0.797 nm. When the Mn 2+ doping content was increased from 0 to 0.12, the energy transfer efficiency (Ce 3+ ,Tb 3+  → Mn 2+ ) gradually increased from 0% to 58%. The Ce 0.67 Tb 0.33 Mg 0.88 Mn 0.12 Al 11 O 19 sample exhibits 105% of the standard NTSC color gamut. Results indicate that Ce 0.67 Tb 0.33 Mg 0.88 Mn 0.12 Al 11 O 19 green phosphors can be applied to illumination devices and displays.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 38
    facet.materialart.
    Unknown
    Highly Infrared Transparent Nanometric Tetragonal Zirconia Prepared By High-Pressure Spark Plasma Sintering (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: Highly infrared transparent tetragonal ZrO 2 (3 mol% yttria-stabilized) was prepared by means of high-pressure spark plasma sintering (HP-SPS). The crystallite size of the resulting dense sample was about 80 nm. In-line transmittance for the 1.5 mm thick sample ranged between 63% and 67% in the wavelength of 3–5 μm, representing 81%–87% of the theoretic value. Meanwhile, the cutoff wavelength of tetragonal ZrO 2 was superior to the values of other high-strength transparent ceramics. This study highlighted the efficiency and simplicity of HP-SPS for obtaining transparent tetragonal ZrO 2 and the great potential of this ceramic applied for durable infrared windows.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 39
    facet.materialart.
    Unknown
    Preparation of Sizable and Uniform-Sized Spherical Ceramic Foams: Drop-in-Oil and Agar Gelation (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: We propose a simple and environmentally friendly method to prepare uniform-sized spherical ceramic foams (SCFs) with excellent pore properties by combining a drop-in-oil method with agar gelation. In addition, the change in size distribution and uniformity (characterized as coefficient of variation (C.V.)) and the corresponding pore-related properties for the SCFs were systematically investigated as functions of agar concentration (i.e., 0.50–1.50 wt% with respect to dry alumina). The results showed that uniform-sized SCFs were successfully fabricated regardless of agar concentration, that pore-related properties were gradually improved by increasing the agar content, and that the most uniform-sized SCFs were obtained when the agar concentration was 1.00 wt%. The extent of the improvement in size uniformity was evaluated by comparing the C.V. value for the drop-in-oil method with that for the pseudo-double-emulsion (PDE) method, which is an alternative method to fabricate SCFs. The C.V. values for the SCFs prepared by the drop-in-oil and the PDE method were determined to be 7% and 31%, respectively. The results clearly indicate that the size uniformity of the SCFs has been much improved for the drop-in-oil method as compared to the PDE method.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 40
    facet.materialart.
    Unknown
    Preparation and Piezoelectricity of NaNbO3 High-Density Ceramics by Molten Salt Synthesis (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: Nanostructures of crystalline orthorhombic sodium niobate (NaNbO 3 ) were synthesized by a molten salt synthesis procedure. As a comparison, an auxiliary experiment via conventional solid state reaction process was carried out simultaneously. The microstructure and morphology evolution of the synthesized nano particles were investigated in detail, and on the basis of the experimental results, an in situ transformation mechanism has been proposed to elucidate the formation processes of NaNbO 3 microstructures. It was found that both the initial shape of the Nb 2 O 5 and the dissolution rate of the initial precursors critically determine the final shapes of the products. Furthermore, the determined electrical properties of the as-obtained products indicated that NaNbO 3 ceramic derived from nanostructures holds the real characteristic of ferroelectric and the polarization–electric field ( P–E ) hysteresis behavior is greatly influenced by the polarization treatment. The obtained NaNbO 3 ceramic after the polarizing treatment exhibited piezoelectric property, d 33  = 28 pC/N.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 41
    facet.materialart.
    Unknown
    Synthesis and Characterization of YB4 Ceramics (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: Yttrium tetraboride was synthesized by reactions of Y 2 O 3 with B 4 C or with a B 4 C/C mixture. Fully dense YB 4 ceramics were prepared by hot-pressing at 1800°C and 20 MPa in He. The flexural strength and microhardness of the YB 4 were about 300 MPa and 27 GPa, respectively. Pure YB 4 showed considerable oxidation above 1200°C. The effect of SiC, AlN, and AlN/SiC on the properties of YB 4 ceramics was characterized. No chemical interactions were identified in the YB 4 –SiC and YB 4 –AlN pseudo binaries. The addition of SiC improved the oxidation resistance below 1200°C. At higher temperatures, the low viscosity of a surface melt caused its continuous runoff and the loss of the oxidation-protection capability of the scale. The addition of AlN/SiC improved the oxidation resistance compared to the ceramics containing only SiC, which was attributed to the presence of Al 2 O 3 in the Y 2 O 3 –SiO 2 –B 2 O 3 glass leading to an increase in its viscosity and preventing glass runoff. A significant improvement in the oxidation resistance of the YB 4 ceramics and extension of their oxidation stability to 1400°C was accomplished by the introduction of AlN only.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 42
    facet.materialart.
    Unknown
    Energy Transfer Enhancement in Eu3+, Tb3+-Doped SiO2 Inverse Opal Photonic Crystals (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: The energy transfer from Tb 3+ to Eu 3+ -doped SiO 2 (SiO 2 :Eu 3+ , Tb 3+ ) inverse opal photonic crystals was investigated by photoluminescence and fluorescence lifetime. The results showed that the photonic band gap enhanced energy transfer from the donor Tb 3+ to the acceptor Eu 3+ . When the fluorescence emission wavelength of Tb 3+ overlaps the photonic band gap, the fluorescence intensity of Tb 3+ is suppressed, and the fluorescence intensity of Eu 3+ is increased because of the enhancement of energy transfer. In addition, the fluorescence lifetime of Tb 3+ decreased.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 43
    facet.materialart.
    Unknown
    The Orientation Distributions of Lines, Surfaces, and Interfaces around Three-Phase Boundaries in Solid Oxide Fuel Cell Cathodes (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: Three-dimensional electron backscatter diffraction was used to measure the crystallographic distribution of the electrochemically relevant triple phase boundary lines and surfaces near them in SOFC cathodes made up of a porous mixture of yttria-stabilized zirconia and lanthanum strontium manganese oxide, both before and after mild electrochemical loading. All distributions were observed to be nearly isotropic, but non-random textures above the detection threshold were observed. The distributions differ between the two cells, as do the phase fractions and the electrochemical history. The different distributions are interpreted as evidence that steady-state distributions vary locally with phase fractions or that they evolve during the initial operation of the fuel cell. The rates at which triple lines, pore surfaces, and interface boundaries in the porous mixture approach a steady-state value appear to decrease with the average amount of mass transport required to reorient that specific feature. This work provides initial insights into the crystallography of interfaces in a multiphase ceramic material.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 44
    facet.materialart.
    Unknown
    Optimization of PST Thin Films Grown by Sputtering and Complete Dielectric Performance Evaluation: An Alternative Material for Tunable Devices (2011)
    Wiley
    Details
    Publication Date: 2011-06-25
    Description: Pb x Sr 1-x TiO 3 (PST) thin films with the ratio Pb/Sr = 40/60 were deposited on silicon substrate with Pt or LaNiO 3 (LNO) bottom electrodes by radio frequency magnetron sputtering followed by a postannealing treatment. The structural and microstructural analyses were performed and a perovskite phase was obtained whatever the nature of the bottom electrodes and even at a low temperature (450°C). The optimal annealing temperature is 650°C at which the films have a dense and fine microstructure. For electrical characterization the different top electrodes (Pt and LNO) were used. In both cases, we demonstrate that PST films present excellent performances in terms of dielectric properties and in particular, the tunability and Figure of Merit. A large tunability (57% at 400 kV/cm) and low dielectric losses (1.4%) were measured at 10 kHz for Pt/PST/Pt structures postannealed at 500°C. For LNO/PST/LNO structures, postannealed at 650°C, the improved tunability (≈80%) and low loss factor (≈2%) were obtained. Prospects of PST as an alternative to BST for tunable applications with a real potentiality of monolithic integration with silicon, in terms of thermal budget, are considered.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 45
    facet.materialart.
    Unknown
    Evaluation of velocity-related approximations in the nonlinear shallow water equations for the Kuril Islands, 2006 tsunami event at Honolulu, Hawaii (2011)
    Wiley
    Details
    Publication Date: 2011-06-29
    Description: The Nonlinear Shallow Water Equations (NSWE) provide a model for long wave behavior commonly used in tsunami modeling problems in which the scale associated with the surface wavelength is much greater than the ocean depth. This approximation allows for the derivation of the NSWE under the assumptions that the pressure is hydrostatic and the horizontal velocity components uniform along the water column. The present study uses current velocity data acquired by the Kilo Nalu Near-Shore Reef Observatory Acoustic Doppler Current Profiler (ADCP) on the south shore of Oahu (21.288°N, 157.865°W) in the aftermath of the 2006 Kuril tsunami to assess the validity of the NSWE assumptions on the velocity components. ADCP measurements provide information on all three velocity components along the water column, allowing the calculation of terms discarded in the NSWE approximation, containing temporal or vertical derivatives. Comparison of the relative magnitude of terms retained and neglected in the NSWE reveals that in shallow waters (10 m) the size of discarded terms remains smaller, but approaches the order of magnitude of retained terms in the momentum equations. Not all terms present in the equations can be evaluated from the available data, so verification of the assumptions investigated here represents a necessary but not sufficient condition for the validity of the NSWE approximation to model tsunami waves in shallow coastal waters.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 46
    facet.materialart.
    Unknown
    Water vapor intrusions into the High Arctic during winter (2011)
    Wiley
    Details
    Publication Date: 2011-06-29
    Description: The meridional transport of water vapor into the High Arctic, accompanied by dry enthalpy and clouds, impacts the surface radiative forcing. The evolution of one such moist intrusion over 9–11 February 2010 is presented. The event is analyzed using a unique blend of measurements including a new pan-Arctic retrieval of column water vapor from the Microwave Humidity Sounders, water vapor profiles from a Raman lidar and a ground-based microwave radiometer at the Polar Environment Atmospheric Research Laboratory (PEARL), in Eureka (80°N, 86°W), on Ellesmere Island in the Canadian High Arctic. A radiation model reveals the intrusion is associated with a 17 W m−2 average increase in downwelling longwave irradiance. Optically thin clouds, as observed by the lidar, contribute a further 20 W m−2 to the downwelling longwave irradiance at their peak. Intrusion events are shown to be a regular occurrence in the Arctic winter with implications for the understanding of the mechanisms driving Arctic Amplification.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 47
    facet.materialart.
    Unknown
    Probabilistic multi-model ensemble predictions of nitrogen concentrations in river systems (2011)
    Wiley
    Details
    Publication Date: 2011-06-29
    Description: Because of an increasing human pressure on the naturally balanced nitrogen cycle, eutrophication-driven hypoxia and corresponding dead zones have multiplied over the last years. Models are used to predict the nitrogen balances and develop mitigation scenarios for such systems. Due to the very complex interaction of water and nitrogen fluxes, no single model structure has been commonly adopted to describe the fluxes best and modeling results often differ substantially. Relying on a single model prediction only can be therefore highly uncertain. Here we illustrate the potential advantage of using a probabilistic multi-model ensemble approach in comparison to predictions of each of its members. Evaluation of corresponding skills and potential economic values to correctly predict a 2 mg N/L target of total nitrogen concentration in the water flowing out of a catchment in south-west Western Australia is conducted. Results show that the ensemble has always more skill and almost always more potential economic value than any of its four members and that it therefore constitutes a more reliable choice in the decision-making process.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 48
    facet.materialart.
    Unknown
    Aqueous OH oxidation of ambient organic aerosol and cloud water organics: Formation of highly oxidized products (2011)
    Wiley
    Details
    Publication Date: 2011-06-10
    Description: Aqueous chemistry can play a vital role in secondary organic aerosol (SOA) formation and aging. A novel analytical approach that allows for simultaneous photo-oxidation and atomization of reacting bulk solutions coupled to an aerosol mass spectrometer (AMS) investigates aqueous OH oxidation of ambient biogenic SOA, cloud water from a biogenic environment, glyoxal, and mixtures of glyoxal with α-pinene SOA components. This is the first study of aqueous oxidative aging of ambient SOA and cloud water organics. Starting with an AMS-based observational framework, we show that aqueous oxidation of biogenic SOA in the presence of glyoxal can better represent observed atmospheric aging than when glyoxal is absent. Oxidation of glyoxal alongside semi-volatile SOA components leads to the production of highly oxidized SOA.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 49
    facet.materialart.
    Unknown
    The stratigraphic filter and bias in measurement of geologic rates (2011)
    Wiley
    Details
    Publication Date: 2011-06-10
    Description: Erosion and deposition rates estimated from the stratigraphic record frequently exhibit a power-law dependence on measurement interval. This dependence can result from a power-law distribution of stratigraphic hiatuses. By representing the stratigraphic filter as a stochastic process called a reverse ascending ladder, we describe a likely origin of power-law hiatuses, and thus, rate scaling. While power-law hiatuses in certain environments can be a direct result of power-law periods of stasis (no deposition or erosion), they are more generally the result of randomness in surface fluctuations irrespective of mean subsidence or uplift. Autocorrelation in fluctuations can make hiatuses more or less heavy-tailed, but still exhibit power-law characteristics. In addition we show that by passing stratigraphic data backward through the filter, certain statistics of surface kinematics from their formative environments can be inferred.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 50
    facet.materialart.
    Unknown
    Enhanced 2.7 μm Emission from Er3+/Tm3+/Pr3+ Triply Doped Fluoride Glass (2011)
    Wiley
    Details
    Publication Date: 2011-06-10
    Description: The 2.7 μm emission has been obtained using 980 nm laser excitation in Er 3+ /Tm 3+ /Pr 3+ triply doped ZrF 4 –BaF 2 –LaF 3 –AlF 3 –YF 3 glass. 2.7 μm emission characteristics and energy transfer are investigated. Population inversion between the 4 I 11/2 and 4 I 13/2 levels is significantly enhanced by way of Tm 3+ and Pr 3+ co-doping into Er 3+ -doped fluoride glass. These results indicate that this Er 3+ /Tm 3+ /Pr 3+ triply doped fluoride glass has potential applications in 2.7 μm laser.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 51
    facet.materialart.
    Unknown
    Microstructural, Electrical, and Magnetic Properties of Acceptor-Doped Nanostructured Lead Zirconate Titanate (2011)
    Wiley
    Details
    Publication Date: 2011-06-10
    Description: The changes in the ferroelectric and magnetic properties of the nanostructured Pb(Zr 0.52 Ti 0.48 ) 1-x Fe x O 3 (0 ≤ x ≤ 0.06) due to the doping of different amounts of acceptor ions (Fe 3+ ) have been studied. X-ray diffraction studies show that the system maintains the tetragonal phase up to the doping of 2 mol% of Fe 3+ and the formation of secondary phase magnetoplumbite (PbFe 12 O 19 ) on further doping. Electron paramagnetic resonance studies have revealed the formation of defect centers which in turn arise due to the interaction of Fe 3+ ions with oxygen vacancies, which are generated in the lattice. This results in the appearance of room temperature ferromagnetic (RTFM) behavior in the doped samples. The dielectric studies reveal that with the concentration of Fe 3+ the peak near the maxima of dielectric constant (ε′ m ) is broadened. Studies of the defect dipoles on the ferroelectric properties have been performed by polarization measurement. The variations of the above properties with the structural and morphological features of the samples have also discussed.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 52
    facet.materialart.
    Unknown
    Preparation and Characterization of High-Purity Metal Fluorides for Photonic Applications (2011)
    Wiley
    Details
    Publication Date: 2011-06-10
    Description: We combine chelate-assisted solvent extraction (CASE) and hot hydrogen fluoride gas treatment to enable a general method for the preparation of high-purity binary metal fluorides. The fluorozirconate glass ZBLANI:Yb 3+ (ZrF 4 –BaF 2 –LaF 3 –AlF 3 –NaF–InF 3 –YbF 3 ), a solid-state laser-cooling material, is used as a test case to quantitatively assess the effectiveness of the purification method. The reduction of transition-metal and oxygen-based impurities is quantified directly by inductively coupled plasma mass spectrometry (ICP-MS) and indirectly by laser-induced cooling, respectively. The concentrations of Cu, Fe, Co, Ni, V, Cr, Mn, and Zn impurities in the ZrCl 2 O precursor solution were measured individually by ICP-MS at various stages of the purification process. CASE was found to reduce the total transition-metal concentration from 72500 to ~100 ppb. Laser cooling was most efficient in ZBLANI:Yb 3+ glass fabricated from CASE-purified metal fluoride precursors, confirming the results of the ICP-MS analysis and demonstrating the effectiveness of the purification methods in a finished optical material. High-purity metal fluorides prepared by the methods presented herein will enable new high-performance optical materials for solid-state optical refrigerators, crystals for vacuum ultraviolet (VUV) spectroscopy of the Thorium-229 nucleus, VUV optics, fibers, and thin-film coatings.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 53
    facet.materialart.
    Unknown
    Aftershock study and seismotectonic implications of the 8 March 2010 Kovancılar (Elazığ, Turkey) earthquake (MW = 6.1) (2011)
    Wiley
    Details
    Publication Date: 2011-06-11
    Description: A destructive earthquake (Mw = 6.1) occurred on the northeast end of the Palu segment of the East Anatolian Fault System (EAFS, eastern Turkey) on 8 March 2010. The spatial distribution of aftershocks suggests that the Palu segment does not terminate to the east of Palu town but extends in the N50°E direction where it has produced a 30 km right stepover. Aftershock depths indicate a seismogenic brittle zone of about 15 km depth. The stress changes on the segments due to recorded events might have loaded more than 0.5 bars of stress on the NE end of the Palu segment and the SW end of the Göynük segment. Therefore, a future earthquake on both segments may occur sooner than was expected before the occurrence of the Mw 6.1 earthquake on 8 March 2010.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 54
    facet.materialart.
    Unknown
    Extinction and optical depth of contrails (2011)
    Wiley
    Details
    Publication Date: 2011-06-14
    Description: One factor limiting the understanding of the climate impact from contrails and aircraft induced cloud modifications is the accurate determination of their optical depth. To this end, 14 contrails were sampled for 2756 s with instruments onboard the research aircraft Falcon during the CONCERT (CONtrail and Cirrus ExpeRimenT) campaign in November 2008. The young (
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 55
    facet.materialart.
    Unknown
    Hi-NicalonTM-SSiC Fiber Oxidation and Scale Crystallization Kinetics (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: The oxidation and scale crystallization kinetics of Hi-Nicalon TM -S SiC fibers were measured after oxidation in dry air between 700° and 1400°C. Scale thickness, composition, and crystallization were characterized by TEM with EDS, supplemented by SEM and optical microscopy. TEM was used to distinguish oxidation kinetics of amorphous and crystalline scales. Oxidation initially produces an amorphous silica scale that incorporates some carbon. Growth kinetics of the amorphous scale was analyzed using the flat-plate Deal-Grove model. The activation energy for parabolic oxidation was 248 kJ/mol. The scales crystallized to tridymite and cristobalite, starting at 1000°C in under 100 h and 1300°C in under 1 h. Crystallization kinetics had activation energy of 514 kJ/mol with a time growth exponent of 1.5. Crystalline silica nucleated at the scale surface, with more rapid growth parallel to the surface. Crystalline scales cracked from thermal residual stress and phase transformations during cool-down, and during oxidation from tensile hoop growth stress. High growth shear stress was inferred to cause intense dislocation plasticity near the crystalline SiO 2 –SiC interphase. Crystalline scales were thinner than amorphous scales, except where growth cracks allowed much more rapid oxidation.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 56
    facet.materialart.
    Unknown
    Melt extraction pathways at segmented oceanic ridges: Application to the East Pacific Rise at the Siqueiros transform (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Throughout the global mid-ocean ridge system, transform faults offset spreading centers. Conductive cooling may be more efficient beneath transform faults, producing a thickened lithosphere that directs melt away from the transform. However, recent observations of thickened crust along transform faults at fast ridges suggest melt redistribution toward transforms, intra-crustal melt production, or efficient extraction of melt. We apply a 3-D model of melt migration and extraction along an oceanic transform domain bounded by ridge segments. Melt is assumed to travel vertically before collecting and migrating beneath a low-permeability boundary inclined towards the ridge axis. A melt extraction zone, which may be geologically interpreted as the presence of faults and/or dikes leading to rapid lateral and vertical melt migration toward plate boundaries, affects the pattern of crustal accretion at segmented ridges. First, we examine a generic ridge-transform-ridge geometry and then a model that represents the Siqueiros transform on the East Pacific Rise. On the basis of crustal thickness variations within the intra-transform spreading centers along the fast-slipping Siqueiros fault, we constrain the presence of a melt extraction zone within 10 km of the transform zone.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 57
    facet.materialart.
    Unknown
    Did aboriginal vegetation burning impact on the Australian summer monsoon? (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Aboriginal vegetation burning practices and their role in the Australian environment remains a central theme of Australian environmental history. Previous studies have identified a decline in the Australian summer monsoon during the late Quaternary and attributed it to land surface-atmosphere feedbacks, related to Aboriginal burning practices. Here we undertake a comprehensive, ensemble model evaluation of the effects of a decrease in vegetation cover over the summer monsoon region of northern Australia. Our results show that the climate response, while relatively muted during the full monsoon, was significant for the pre-monsoon season (austral spring), with decreases in precipitation, higher surface and ground temperatures, and enhanced atmospheric stability. These early monsoon season changes can invoke far-reaching ecological impacts and set-up land surface-atmosphere feedbacks that further accentuate atmospheric stability.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 58
    facet.materialart.
    Unknown
    Spatial performance of four climate field reconstruction methods targeting the Common Era (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: The spatial skill of four climate field reconstruction (CFR) methods is investigated using pseudoproxy experiments (PPEs) based on two millennial-length general circulation model simulations. Results indicate that presently available global and hemispheric CFRs for the Common Era likely suffer from spatial uncertainties not previously characterized. No individual method produced CFRs with universally superior spatial error statistics, making it difficult to advocate for one method over another. Northern Hemisphere means are shown to be insufficient for evaluating spatial skill, indicating that the spatial performance of future CFRs should be rigorously tested for dependence on proxy type and location, target data and employed methodologies. Observed model-dependent methodological performance also indicates that CFR methods must be tested across multiple models and conclusions from PPEs should be carefully evaluated against the spatial statistics of real-world climatic fields.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 59
    facet.materialart.
    Unknown
    European cold winter 2009–2010: How unusual in the instrumental record and how reproducible in the ARPEGE-Climat model? (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Boreal winter 2009–2010 made headlines for cold anomalies in many countries of the northern mid-latitudes. Northern Europe was severely hit by this harsh winter in line with a record persistence of the negative phase of the North Atlantic Oscillation (NAO). In the present study, we first provide a wider perspective on how unusual this winter was by using the recent 20th Century Reanalysis. A weather regime analysis shows that the frequency of the negative NAO was unprecedented since winter 1939–1940, which is then used as a dynamical analog of winter 2009–2010 to demonstrate that the latter might have been much colder without the background global warming observed during the twentieth century. We then use an original nudging technique in ensembles of global atmospheric simulations driven by observed sea surface temperature (SST) and radiative forcings to highlight the relevance of the stratosphere for understanding if not predicting such anomalous winter seasons. Our results demonstrate that an improved representation of the lower stratosphere is necessary to reproduce not only the seasonal mean negative NAO signal, but also its intraseasonal distribution and the corresponding increased probability of cold waves over northern Europe.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 60
    facet.materialart.
    Unknown
    Atmospheric chemistry in stereo: A new look at secondary organic aerosols from isoprene (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Isoprene, a compound emitted by vegetation, could be a major contributor to secondary organic aerosols (SOA) in the atmosphere. The main evidence for this contribution were the 2-methylbutane-1,2,3,4-tetraols, or 2-methyltetrols (2-methylerythritol and 2-methylthreitol) present in ambient aerosols. In this work, the four stereoisomers of these tetraols were analyzed in aerosols from Aspvreten, Sweden. 2-C-methyl-D-erythritol was found in excess over its enantiomer in the Spring/Summer, by up to 29% in July. This clearly indicated some biological origins for this enantiomer, consistent with its well-documented production by plants and other living organisms. In addition, a minimum of 20 to 60% of the mass of racemic tetraols appeared from biological origin. Thus, the SOA mass produced by isoprene in the atmosphere is less than what indicated by the 2-methyltetrols in aerosols. Our results also demonstrate that stereochemical speciation can distinguish primary and secondary organic material in atmospheric aerosols.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 61
    facet.materialart.
    Unknown
    Relation between single very-long-period pulses and volcanic gas emissions at Mt. Asama, Japan (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Multiple volcanic observations conducted at Mt. Asama, Japan, provide evidence of a link between single very-long-period (VLP) seismic pulses and volcanic gas emissions. SO2 flux measurements were conducted on 2 June 2009, when Mt. Asama was producing ash-free eruptions with VLP pulses. Gas bursts from a vent at the crater bottom following the VLP pulses provided an excellent opportunity to examine the relation directly. The SO2 emission for each eruption was calculated by integrating high temporal SO2 flux data obtained by the SO2 imaging system and subtracting the contribution from quiescent degassing from fumaroles around the crater bottom. A seismic moment of VLP pulse was estimated by the waveform inversion. We observed seven eruptions and obtained the proportional relation between VLP pulse moment and SO2 emission. The relation determined is consistent with the VLP source model; these observational results are the first report of a quantitative comparison between single VLP pulse moment and volcanic gas emission.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 62
    facet.materialart.
    Unknown
    Influence of pre-existing volcanic edifice geometry on caldera formation (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Volcanic edifice construction at the Earth's surface significantly modifies the stress field within the underlying crust with two main implications for caldera formation. First, tensile rupture at the Earth's surface is favored at the periphery, which enables ring fault formation. Second, edifice formation amplifies the amount of pressure decrease occurring within a magma reservoir before the eruption stops. Taking into account both of these effects, caldera formation can be initiated during a central eruption of a pre-existing volcano even when assuming elastic behaviour for the surrounding crust. Providing the roof aspect ratio is small enough, conditions for caldera formation by reservoir withdrawal can be reached whatever the reservoir shape is. However ring fault initiation is easier for laterally elongated reservoirs.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 63
    facet.materialart.
    Unknown
    In situ Transmission Electron Microscopy Study on the Phase Transitionsin Lead-Free (1−x)(Bi1/2Na1/2)TiO3–xBaTiO3 Ceramics (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: The phase transitions in unpoled lead-free (1− x )(Bi 1/2 Na 1/2 )TiO 3 – x BaTiO 3 ( x = 0.06 and 0.11) ceramics are investigated using hot-stage transmission electron microscopy (TEM). It is found that large ferroelectric domains in both ceramics start to disappear around T d , the depolarization temperature. After the transition, both compositions exhibit the P 4 bm tetragonal symmetry in the form of nanodomains. The structural transition observed by the in situ TEM experiments seems to be gradual and occurs within a temperature range of several tens of degrees, in contrast to the sharp anomaly at T d revealed by the dielectric characterization. With further increasing temperature, no structural change was observed for both compositions across T RE , where the dielectric frequency dispersion vanishes, and T m , where the dielectric permittivity reaches maximum. The tetragonal-to-cubic transition is diffuse and takes place in a broad temperature window well above both T RE and T m . These results of structural phase transitions are summarized in a phase diagram with its composition range covering the morphotropic phase boundary (MPB).
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 64
    facet.materialart.
    Unknown
    Solvo-Thermal Synthesis and Characterization of Indium Selenide Nanocrystals (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Zinc-blende-type cubic InSe and β-In 2 Se 3 crystallites were synthesized using the solvo-thermal method in this study. The crystalline structure, electronic and optical characterization of indium selenide particles were investigated using transmission electron microscopy (TEM), X-ray diffractometer (XRD), UV–visible absorbance spectra. It was observed that the dominant crystalline structure of samples synthesized at 180°C for 1.5–48 h is zinc-blende-type cubic InSe phase with lattice parameter of about 0.573 nm. As the reaction temperature was raised to 200°C, the zinc-blende-type cubic InSe phase diminished and the β-In 2 Se 3 phase was produced. The zinc-blende-type cubic InSe phase band gap is about 1.68 eV. These synthesized compounds provide promising candidates for solar cell applications.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 65
    facet.materialart.
    Unknown
    Color Tunable Upconversion Emission in Yb, Er Co-Doped Bismuth Titanate Inverse Opal (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Upconversion emission of Yb, Er co-doped Bi 4 Ti 3 O 12 (Bi 4 Ti 3 O 12 : Yb, Er) inverse opal photonic crystals was investigated. Strong green (548 nm) and red (660 nm) upconversion emission bands were observed under a 980 nm excitation at room temperature. The results showed that the intensity of upconversion emission bands can be tuned by controlling the structure of the inverse opal. Significant suppression of the green or red upconversion emission was obtained if the photonic band gap overlaps with the Er 3+ ions emission band, resulting in color tunable up-conversion photonic crystals with applications in solid-state color displays.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 66
    facet.materialart.
    Unknown
    FIB Tomographic Analysis of Subsurface Indentation Crack Interactions with Pores in Alumina (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: This article describes a study involving three-dimensional FIB tomographic characterization of Vickers microindentation sites in an alumina material containing pores. The study was carried out using a dual beam FIB instrument for loads in the range 50–200 g. The results obtained show that this technique can be used to obtain 3-D distributions of indentation-generated cracks. Although, compared to a dense material, presence of pores in alumina reduced the ability to generate and/or propagate radial cracks, the significant probability of crack-pore interactions indicates that pores assist in the generation/propagation lateral cracks. The subsurface images show that pores act as sites for crack initiation and/or assist in crack propagation. In addition, a clearly reduced ability to generate and/or propagate radial cracks has been noted. However, considering that FIB tomography is destructive and invasive, microstructural changes seem to have occurred during the process and consequently it is not possible to identify all the generated cracks. Moreover, propagation of some of the cracks also occurred due to material removal in FIB milling.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 67
    facet.materialart.
    Unknown
    Synthesis of Mesoporous Carbon-Bonded TiC/SiC Composites by Direct Carbothermal Reduction of Sol–Gel Derived Monolithic Precursor (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Mesosporous carbon-bonded titanium-carbide/silicon-carbide (C-TiC/SiC) ceramics with a high specific surface area (221 m 2 /g), ultra fine grains (10–50 nm), and high crystallinity were synthesized from direct carbothermal reduction (1100°–1450°C) of monolithic Ti–Si–O–C precursors made from controlled sol–gel process. The nano-sized carbide grains are bonded into bulk materials by poly(furfuryl alcohol) (PFA) derived nanocrystalline carbon framework by “bridge,” “entanglement,” and “adhesive” effects. Graphenes were found to grow on {111} planes of TiC grains but this was not observed for SiC. The bonding of graphitic carbon layers on carbide grains support the nanostructure and also result in the desired combination of functional and mechanical properties.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 68
    facet.materialart.
    Unknown
    High Temperature Infrared Properties of YSZ Electrolyte Ceramics for SOFCs: Experimental Determination and Theoretical Modeling (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: Infrared radiative properties of 8-mol%-yttria-stabilized zirconia (8YSZ) ceramics of porosity 3% as applied as electrolyte for solid oxide fuel cells (SOFCs) were studied at room and elevated temperatures in the wavelength range from 2 to 20 μm. The room-temperature directional-hemispherical measurements of reflectance and transmittance for thin samples were combined with normal emittance measurements at several temperatures up to 1700 K. The use of the radiation transfer theory in a region of semi-transparency enabled identification of absorption and scattering properties of the material. Both a detailed numerical procedure using the known discrete ordinates method and a novel iterative analytical solution were employed. An analysis based on the Mie theory confirms volumetric scattering by sub-micron size polydisperse pores in the ceramics. It is shown that the absorption coefficient of 8YSZ increases considerably with temperature. This effect should be taken into account in combined heat transfer calculations for SOFCs.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 69
    facet.materialart.
    Unknown
    Sol–Gel Processing and Characterizations of a Ba0.75Sr0.25Ti 0.95Zr0.05O3 Ceramic (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: A Ba 0.75 Sr 0.25 Ti 0.95 Zr 0.05 O 3 ceramic was developed for use in nonlinear transmission line (NLTL) applications. The sol–gel process was used to synthesize Ba 0.75 Sr 0.25 Ti 0.95 Zr 0.05 O 3 nanoparticles to achieve a uniform composition and a high surface area. Simultaneous thermal gravimetric analysis and differential thermal analysis (TGA/DTA) was used to identify the decomposition sequence as a function of temperature for the as-synthesized powders. The phase transformation was confirmed by X-ray diffraction (XRD). The calcined nanoparticles were hot-pressed at 1300°C to achieve a high density. Microstructures were characterized using scanning electron microscopy (SEM). Several dielectric properties were measured and are reported.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 70
    facet.materialart.
    Unknown
    Strength of Highly Porous Ceramic Electrodes (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Highly porous ceramics are critical components of Solid Oxide Fuel Cells. Nevertheless, their mechanical properties are poor and not fully understood. Herein, Discrete Element simulations are used to quantitatively assess the relation between the particulate microstructure of highly porous ceramics and their mechanical properties. Partially sintered ceramics are numerically generated with complex microstructures including pore formers and bilayers. These microstructures are then tested in tension and compression to obtain their elastic and fracture behavior. Compiling experimental data from the literature and simulations results, an Orowan–Petch type relation between strength and particle size is proposed for highly porous ceramics. It is based on the local fracture model at the length scale of solid bonds between sintered particles.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 71
    facet.materialart.
    Unknown
    Ultra-Broadband Near-Infrared Luminescence of Ni2+: ZnO–Al2O3–SiO2 Nanocomposite Glasses Prepared by Sol–Gel Method (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: We have studied the synthesis and near-infrared luminescent properties of Ni 2+ -doped ZnO–Al 2 O 3 –SiO 2 nanocomposite glasses embedded activated spinel nanocrystals prepared using a sol–gel technique. Nanocrystal-dependent optical properties in Ni 2+ -doped nanocomposite glasses were systematically investigated. We found that Ni 2+ ion is optically active only in the composite embedded nanocrystals, which can provide octahedral position with appropriate crystal field strength. Near-infrared emission ranging from 1100 to 1600 nm was observed in the Ni 2+ -doped composite fabricated by sol–gel method. Such an ultra-broadband luminescence from the nanocomposite could cover the infrared emission bands obtained from multiple rare earth ions (Ho 3+ , Pr 3+ , and Tm 3+ ) doped glasses.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 72
    facet.materialart.
    Unknown
    Effect of the Addition of CaZrO3 and LiNbO3 on the Phase Transitions and Piezoelectric Properties of K0.5Na0.5NbO3 Lead-Free Ceramics (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: The (1- x - y )K 0.5 Na 0.5 NbO 3 - x CaZrO 3 - y LiNbO 3 (KNLNCZ- x - y ) lead-free piezoelectric ceramics were fabricated by conventional technique, and the effect of the addition of CaZrO 3 and LiNbO 3 on the phase transitions and piezoelectric properties of the KNN-based ceramics was investigated. The addition of CaZrO 3 will shift the orthorhombic-rhombohedral transition temperature of the ceramics to above room temperature, and with the increase of the CaZrO 3 additives, a dielectric peak rises up near the orthorhombic-tetragonal phase transition of the ceramics resulting in the spread of the ferroelectric-paraelectric phase transition over a rather wide temperature range due to polar nanoregions arising from composition fluctuation. For x = 0.05, the addition of LiNbO 3 is effective to shift the T R-O and T O-T downward and T C upward in KNLNCZ-0.05- y ceramics. Optimum piezoelectric properties ( d 33 = 216 pC/N and k p = 42.9%) were obtained for the KNLNCZ- x - y ceramics with x = 0.05 and y = 0.07 due to the decrease of T O-T to be around room temperature.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 73
    facet.materialart.
    Unknown
    Thermal Shock Resistance Behavior of Alumina Ceramics Incorporated with Boron Nitride Nanotubes (2011)
    Wiley
    Details
    Publication Date: 2011-06-19
    Description: Alumina-matrix composite containing 2.0 wt% boron nitride nanotubes and monolithic alumina were fabricated by hot pressing, and their thermal and mechanical properties were investigated. Thermal shock resistance was evaluated by water quenching and subsequently by measuring the residual flexural strength by three-point bending test. Though the residual flexural strength of the composite is higher than that of the monolith at temperature differences lower than 280°C, the thermal shock of the composite is more sensitive to temperature change, exhibiting no significant improvement in thermal shock resistance. The variation in thermal shock resistance for the composite is resulted from the introduction of BNNTs.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 74
    facet.materialart.
    Unknown
    Magneto-Electric Properties of Multiferroic Pb(Zr0.52Ti0.48)O3–NiFe2O4 Nanoceramic Composites (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: Bulk 0.7PbZr 0.52 Ti 0.48 O 3 –0.3NiFe 2 O 4 nanoceramic composites with a grain size of ~50 nm were fabricated using chemical synthesis, high-energy ball-milling, and spark plasma sintering. The composite produced broad dielectric constant peaks and frequency dispersion, similar to relaxor ferroelectrics, and was ferroelectric and ferromagnetic. The dielectric and piezoelectric properties of nanoceramics are lower than those of microceramics due to grain-size effects. “Butterfly”-type magnetoelectric (ME) loops indicate that direct stress coupling between magnetostrictive and piezoelectric phases is still active in composite ceramics when the grain size is ~50 nm.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 75
    facet.materialart.
    Unknown
    Onset Plastic Deformation and Cracking Behavior of Silicon Carbide Under Contact Load at Room Temperature (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: The room temperature onset plastic deformation and crack behavior of 3C-SiC under contact load were investigated using nanoindentation and transmission electron microscopy (TEM). During loading, abrupt bursts or pop-in in the load–displacement curves was observed at a depth of ~60 nm. The 3C-SiC deforms elastically before the pop-in depth, but exhibits a plastic-elastic behavior after that. TEM observations reveal that the shear slip is the predominant deformation mechanism in 3C-SiC during indentation. The cracks usually initiate at the intersection of shear bands or grain boundary. In addition, theoretical analysis confirms that the pop-in event is associated with the onset plasticity of 3C-SiC.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 76
    facet.materialart.
    Unknown
    Direct measurements of CO2 flux in the Greenland Sea (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: During summer 2006 eddy correlation CO2 fluxes were measured in the Greenland Sea using a novel system set-up with two shrouded LICOR-7500 detectors. One detector was used exclusively to determine, and allow the removal of, the bias on CO2 fluxes due to sensor motion. A recently published correction method for the CO2-H2O cross-correlation was applied to the data set. We show that even with shrouded sensors the data require significant correction due to this cross-correlation. This correction adjusts the average CO2 flux by an order of magnitude from −6.7 × 10−2 mol m−2 day−1 to −0.61 × 10−2 mol m−2 day−1, making the corrected fluxes comparable to those calculated using established parameterizations for transfer velocity.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 77
    facet.materialart.
    Unknown
    R-Curve Behavior of Pb(Mg1/3Nb2/3)O3-29 mol% PbTiO3 Single Crystals: The Effect of Crystallographic Orientation and Grain Structure (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: The crack growth resistance behavior of single crystal and polycrystalline 0.71Pb(Mg 1/3 Nb 2/3 )O 3 -0.29PbTiO 3 (PMN-29%PT) was determined with compact-tension specimens. Two different single crystal orientations were produced by the solid-state crystal growth technique (SSCG) and characterized, allowing for the direct comparison to polycrystalline material. Single crystal R -curve behavior was observed to be anisotropic, which is explained by the effects of ferroelasticity and stress-induced phase transformations on toughening. Results of the polycrystalline samples display comparable toughness to that observed in single crystal measurements.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 78
    facet.materialart.
    Unknown
    Certification of A Boron Carbide Powder Reference Material for Chemical Analysis (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: The certification of a boron carbide reference material for chemical composition is described. The mass fractions of 16 elements and two boron species are certified in an international interlaboratory comparison with 35 participating laboratories from six different countries. Beside chemical characterization the certification process includes homogeneity and stability testing of the candidate material boron carbide (type F360, 305M422). Details of the analytical methods used for chemical characterization and of the calculation of the uncertainties of the certified mass fractions are given. The new reference material ERM ® -ED102 with certified mass fractions of 18 parameters (elements and species) and of the amount fraction of the isotope 10 B is a valuable tool for laboratories working in the field of advanced ceramic materials analysis to improve their analytical results.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 79
    facet.materialart.
    Unknown
    Enhanced Densification and Thermoelectric Performance of In4Sn3O12 by Reactive Sintering in the In-Sn-Ga-O System (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: The thermoelectric properties of the fluorite-related oxide, In 4 Sn 3 O 12 , have been investigated by studying the system In 4− x Ga x Sn 3 O 12 , with 0 ≤  x  ≤   0.15. It has been shown that Ga does not enter the In 4 Sn 3 O 12 matrix, and two secondary phases form via the Ga introduction: SnO 2 and Ga 2 In 6 Sn 2 O 16 . By reactive sintering between In 2 O 3 , SnO 2 , and Ga 2 O 3 precursors, the density of the samples is considerably increased from 66% (actual density/theoretical density) for x  =   0 up to 90% for x  =   0.15, which significantly decreases the electrical resistivity. This is attributed to the large number of grain boundaries localized among the secondary phases, which inhibit the grain growth and hence favor the densification. The phase In 4 Sn 3 O 12 is for the first time reported to exhibit a semi-metallic behavior. The Seebeck coefficient does not change significantly with respect to the pristine matrix in accordance with the fact that Ga does not play any role as a doping agent. The thermal conductivity increases with the Ga content. The maximum figure of merit, ZT  = 0.23, at 1000 K obtained at a very low Ga content ( x  =   0.05), is comparable to the value obtained for Ge doped In 2 O 3 ( ZT  ~ 0.3). This study suggests that In 4 Sn 3 O 12 can be a potential material for thermoelectric applications.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 80
    facet.materialart.
    Unknown
    Temperature-Dependent Crystal Structures of Ti2AlN and Cr2GeC as Determined from High Temperature Neutron Diffraction (2011)
    Wiley
    Details
    Publication Date: 2011-06-22
    Description: In this work, we report on the temperature-dependent crystal structures of the isostructural, layered hexagonal phases Ti 2 AlN and Cr 2 GeC determined by Rietveld analysis of high temperature neutron powder diffraction data of fully dense, polycrystalline, bulk samples in the 100° to 1100°C temperature range. For both phases, the A-group atoms, Al and Ge, vibrate with the highest amplitude and do so anisotropically within the basal plane. All bonds expand linearly with temperature, with the highest relative thermal expansion occurring in the Ti–Al and Cr–Ge bonds. The thermal expansion coefficients in the a - and c -direction are, respectively, 10.3(±0.2) × 10 −6 and 9.3(±0.2) × 10 −6  K −1 for Ti 2 AlN and 12.8(±0.3) × 10 −6 and 14.6(±0.3) × 10 −6  K −1 for Cr 2 GeC. The unit cell volume expansions observed by HTND are 10.0(±0.2) × 10 −6  K −1 for Ti 2 AlN and 13.4(±0.3) × 10 −6  K −1 for Cr 2 GeC.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 81
    facet.materialart.
    Unknown
    Sea-level rise and impacts projections under a future scenario with large greenhouse gas emission reductions (2011)
    Wiley
    Details
    Publication Date: 2011-06-23
    Description: Using projections from two coupled climate models (HadCM3C and HadGEM2-AO), we consider the effect on 21st century sea-level rise (SLR) of mitigation policies relative to a scenario of business-as-usual (BAU). Around a third of the global-mean SLR over the century is avoided by a mitigation scenario under which global-mean near surface air temperature stabilises close to the Copenhagen Accord limit of a 2°C increase. Under BAU (a variant of the A1B scenario) the model-averaged projected SLR for 2090–2099 relative to 1980–1999 is 0.29 m–0.51 m (5%–95% uncertainties from treatment of land-based ice melt); under mitigation (E1 scenario) it is 0.17 m–0.34 m. This reduction is primarily from reduced thermal expansion. The spatial patterns of regional SLR are fairly dissimilar between the models, but are qualitatively similar across scenarios for a particular model. An impacts model suggests that by the end of the 21st century and without upgrade in defences around 55% of the 84 million additional people flooded per year globally under BAU (from SLR alone) could be avoided under such mitigation. The above projections of SLR follow the methodology of the IPCC Fourth Assessment. We have, however, also conducted a sensitivity study of SLR and its impacts where the possibility of accelerated ice sheet dynamics is accounted for.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 82
    facet.materialart.
    Unknown
    Shelf resonance and impact of near-field tsunami generated by the 2010 Chile earthquake (2011)
    Wiley
    Details
    Publication Date: 2011-06-23
    Description: The 2010 Chile earthquake of Mw 8.8 generated a destructive tsunami in the near field that resulted in warnings across the Pacific. Numerical modeling shows trapping and amplification of the energy over the continental shelf and slope. A spectral analysis of the computed surface elevation reveals resonance oscillations with periods up to 129 min along the central Chile coast. The temporal and spectral data provides an explanation for the long-period waves recorded by DART buoys and the prolonged wave activities and belated impacts reported by residents and survey teams. The present study of the 2010 Chile tsunami together with those of the 2006 Kuril and 2009 Samoa tsunamis has directly associated shelf resonance with impacts on insular and continental coasts and provided a tool to identify at-risk localities in tsunami hazard assessment.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 83
    facet.materialart.
    Unknown
    Infrasonic detection of a near-Earth object impact over Indonesia on 8 October 2009 (2011)
    Wiley
    Details
    Publication Date: 2011-06-24
    Description: We present analysis of infrasonic signals produced by a large Earth-impacting fireball, believed to be among the most energetic instrumentally recorded during the last century that occurred on 8 October, 2009 over Indonesia. This extraordinary event, detected by 17 infrasonic stations of the global International Monitoring Network, generated stratospherically ducted infrasound returns at distances up to 17 500 km, the greatest range at which infrasound from a fireball has been detected since the 1908 Tunguska explosion. From these infrasonic records, we find the total source energy for this bolide as 8–67 kilotons of TNT equivalent explosive yield, with the favored best estimate near ∼50 kt. Global impact events of such energy are expected only once per decade and study of their impact effects can provide insight into the impactor threshold levels for ground damage and climate perturbations.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 84
    facet.materialart.
    Unknown
    Low seismic resolution cannot explain S/P decorrelation in the lower mantle (2011)
    Wiley
    Details
    Publication Date: 2011-06-29
    Description: Inverted models of the deep mantle show a decorrelation between maps of shear VS and compressional VP wave velocities, an anti-correlation between the bulk sound velocity V$\phi$ and VS and a much larger variability of VS with respect to VP, expressed by large values of the ratio of their relative lateral variations. We carried out synthetic tests to verify if these features could be artifacts, explained by limits in tomographic resolution: synthetic data are calculated for an “input” model, and linearly inverted, as in tomography, to find an “output” model. Comparing the values of the aforementioned parameters for two different chemically homogeneous input models with the associated reconstructed output ones, we found that artifacts caused by realistic data noise and the nonuniform distribution of seismic sources and stations over the globe are not sufficient to introduce the features previously described. We confirm that compositional effects are required to explain them.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 85
    facet.materialart.
    Unknown
    Extreme melt on Canada's Arctic ice caps in the 21st century (2011)
    Wiley
    Details
    Publication Date: 2011-06-09
    Description: Canada's Queen Elizabeth Islands contain ∼14% of Earth's glacier and ice cap area. Snow accumulation on these glaciers is low and varies little from year to year. Changes in their surface mass balance are driven largely by changes in summer air temperatures, surface melting and runoff. Relative to 2000–2004, strong summer warming since 2005 (1.1 to 1.6°C at 700 hPa) has increased summer mean ice surface temperatures and melt season length on the major ice caps in this region by 0.8 to 2.2°C and 4.7 to 11.9 d respectively. 30–48% of the total mass lost from 4 monitored glaciers since 1963 has occurred since 2005. The mean rate of mass loss from these 4 glaciers between 2005 and 2009 (−493 kg m−2 a−1) was nearly 5 times greater than the 1963–2004 average. In 2007 and 2008, it was 7 times greater (−698 kg m−2 a−1). These changes are associated with a summer atmospheric circulation configuration that favors strong heat advection into the Queen Elizabeth Islands from the northwest Atlantic, where sea surface temperatures have been anomalously high.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 86
    facet.materialart.
    Unknown
    A 5200-year record of freshwater availability for regions in western North America fed by high-elevation runoff (2011)
    Wiley
    Details
    Publication Date: 2011-06-09
    Description: Shrinking glaciers and snowpacks are reducing discharge in rivers that drain the central Rocky Mountain region – water that supports downstream societies and ecosystems of western North America. However, a new 5200-year record of Lake Athabasca water-level variations, which serves as a sensitive gauge of past changes in alpine-sourced river discharge, reveals that western Canadian society has developed during a rare period of unusually abundant water ‘subsidized’ by prior glacier expansion. As the ‘alpine water tap’ closes, much drier times are ahead. Future water availability is likely to become similar to the mid-Holocene when Lake Athabasca dropped 2–4 m below the twentieth-century mean. Regions dependent on high-elevation runoff (i.e., western North America) must prepare to cope with impending water scarcity of magnitude not yet experienced since European settlement.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 87
    facet.materialart.
    Unknown
    Synthesis and Photocatalytic Behaviors of High Surface Area BiFeO3 Thin Films (2011)
    Wiley
    Details
    Publication Date: 2011-06-10
    Description: High surface area BiFeO 3 thin films were deposited on ITO substrates by templates method and chemical solution deposition. The resulting phase composition and microstructures were characterized using X-ray diffraction, scanning electron microscopy and Raman spectroscopy. We further demonstrated the useful photocatalytic activity of these films as determined by degradation of Congo red under visible-light irradiation ( λ 〉 400 nm). Our results showed that the surface area have a great effect on the photocatalytic performances of the BiFeO 3 thin films.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 88
    facet.materialart.
    Unknown
    High Ion Conductivity in MgHf(WO4)3 Solids with Ordered Structure: 1-D Alignments of Mg2+ and Hf4+ Ions (2011)
    Wiley
    Details
    Publication Date: 2011-06-10
    Description: We have developed a novel ion conductor comprising magnesium hafnium tungstate (MgHf(WO 4 ) 3 ) as a solid electrolyte for future metal-air batteries. The conductivity of this material measured as 2.5 × 10 −4 S/cm at 600°C is about one order of magnitude higher than that of existing ion conductor with similar structure, such as Sc 2 (WO 4 ) 3 . We have also elucidated for the first time that MgHf(WO 4 ) 3 has an intrinsic crystal structure, forming one-dimensional (1-D) alignments of individual Mg 2+ and Hf 4+ ions alternating within quasi-layered WO 4 2– units at Sc 3+ sites in Sc 2 (WO 4 ) 3 . The structure observed by HAADF-STEM clearly coincides with the results obtained by first principle calculation. The mechanism for high ion conductivity is discussed from the viewpoints of its ordered structure and physical property of negative thermal expansion.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 89
    facet.materialart.
    Unknown
    The reversal of the multi-decadal trends of the equatorial Pacific easterly winds, and the Indonesian Throughflow and Leeuwin Current transports (2011)
    Wiley
    Details
    Publication Date: 2011-06-11
    Description: Multi-decadal weakening trend of the equatorial Pacific easterly winds since 1960 has reversed after 1993. The trend reversal has induced cooling (shallow thermocline) trend in the equatorial western Pacific before 1993, followed by a warming (deep thermocline) trend from 1993 to the present. All available atmospheric reanalysis products corroborate the trend reversal during the two multi-decadal periods. The magnitudes of the multi-decadal trends of the easterly winds, however, differ among the reanalysis products. The trend reversals of regional ocean circulations are assessed using linear regressions between wind and transport anomalies in an eddy-permitting numerical model, suggesting that since 1993 the Indonesian Throughflow and the Leeuwin Current transports have also reversed their multi-decadal weakening trends.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 90
    facet.materialart.
    Unknown
    Impacts of wind stress on the Antarctic Circumpolar Current fronts and associated subduction (2011)
    Wiley
    Details
    Publication Date: 2011-06-14
    Description: Recent studies suggest that the overturning circulation in the Antarctic Circumpolar Current (ACC) region shows a weak sensitivity to overlying wind stress changes, due to balancing of changes in the eddy-induced and Eulerian mean transports. Using an eddy-permitting coupled climate model, we analyze the response of the ACC transport, and associated water mass subduction rates, in response to an idealized poleward shift and intensification of the westerlies. As in previous studies, we find a small increase in the net ACC transport, and a poleward shift in the mean position of the ACC flow. However, the ACC is restructured, with the Subantarctic Front (SAF) and Polar Front (PF) branches shifting poleward by between 0.9° and 2.5° of latitude, resulting in a weaker ACC flow in both the SAF and PF zones. The wind stress anomaly drives a stronger northward Ekman transport of cool surface waters, deepening the winter mixed layer and causing a 12.7 Sv increase in the subduction of Subantarctic Mode Water (SAMW) north of the SAF zone and a 6.5 Sv increase in the subduction of Antarctic Intermediate Water (AAIW) within the SAF and PF zones. Our results suggest that changes in the wind stress restructure the Southern Ocean large-scale circulation, including the flow of the ACC in its primary jets, and that this affects the formation rates of SAMW and AAIW in this complex region.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 91
    facet.materialart.
    Unknown
    The Compaction, Sintering, and Mechanical Properties of Al2O3–CeO2 Composite Nanopowders (2011)
    Wiley
    Details
    Publication Date: 2011-06-15
    Description: In the present work, compaction, sintering behavior, and mechanical properties of Al 2 O 3 –CeO 2 composite nanopowders were investigated. Al 2 O 3 and Al 2 O 3 –CeO 2 composite nanopowders were prepared by a sol–gel method. The effect of CeO 2 on compressibility, sintering rate, final density, and mechanical properties was studied. The aggregation strength of nanopowders reduced from 158 to 101 MPa by adding 5 wt% CeO 2 . The amount of CeO 2 had a strong effect on the sintering behavior and final microstructure of nanopowders and it inhibited alumina grain growth and suppressed densification process. The activation energy for grain growth increased from 428 to 554 kJ/mol by adding 5 wt% CeO 2 to the nanopowders. The addition of 5 wt% CeO 2 improved fracture toughness (by 28%) and flexural strength (by 17%) with respect to monolithic Al 2 O 3 .
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 92
    facet.materialart.
    Unknown
    Oceanic forcing for the East Asian precipitation in pacemaker AGCM experiments (2011)
    Wiley
    Details
    Publication Date: 2011-06-17
    Description: The impact of the tropical oceanic forcing on the East Asian winter-to-early spring climate is investigated by implementing the pacemaker technique in the slab mixed-layer version of the Geophysical Fluid Dynamics Laboratory AM2.1 atmospheric general circulation model. The results demonstrate that oceanic forcing from the deep tropical eastern Pacific (DTEP) can instigate the Pacific-East Asia teleconnection and that the Philippine Sea anticyclone and the associated air-sea interaction are crucial for the realization of the impact of the teleconnection over East Asia. Comparison among cases in which the pace-maker is designated over the DTEP region, DTEP plus the Indian Ocean, and the whole tropical oceans indicates that tropical oceanic forcing outside of the Niño regions can also exert significant influence on East Asian climate. As a result, a total of 30% of the variance of the East Asian precipitation index can be accounted for by the tropical oceanic forcing.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 93
    facet.materialart.
    Unknown
    North Tropical Atlantic influence on western Amazon fire season variability (2011)
    Wiley
    Details
    Publication Date: 2011-06-17
    Description: The prevailing wet climate in the western Amazon is not favorable to the natural occurrence of fires. Nevertheless, the current process of clearing of humid forests for agriculture and cattle ranching has increased the vulnerability of the region to the spread of fires. Using meteorological stations precipitation and the Moderate Resolution Spectroradiometer (MODIS) Active-Fires (AF) during 2000–2009, we show that fire anomalies vary closely with July-August-September (JAS) precipitation variability as measured by the Standardized Precipitation Index (SPI). The precipitation variability is, in turn, greatly determined by sea surface temperature (SST) anomalies in the North Tropical Atlantic (NTA). We develop a linear regression model to relate local fire activity to an index of the NTA-SST. By using seasonal forecasts of SST from a coupled model, we are able to predict anomalous JAS fire activity as early as April. We applied the method to predict the severe 2010 JAS season, which indicated strongly positive seasonal fire anomalies within the 95% prediction confidence intervals in most western Amazon. The spatial distribution of predicted SPI was also in accordance with observed precipitation anomalies. This three months lead time precipitation and fire prediction product in the western Amazon could help local decision makers to establish an early warning systems or other appropriate course of action before the fire season begins.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 94
    facet.materialart.
    Unknown
    Does positioning of the North Pacific Current affect downstream ecosystem productivity? (2011)
    Wiley
    Details
    Publication Date: 2011-06-24
    Description: Fluctuations in the positioning of major ocean currents can influence ecosystem dynamics, but previously the technology has been lacking to make direct observational assessments. Here, we test the hypothesis that positioning of the North Pacific Current (NPC) is related to biological attributes of the central-northern California Current Ecosystem (CCE). To test this hypothesis we use newly available data from the Argo array and compare it with a suite of well-known ecosystem indicators over 6 years, 2002 through 2007. We found increased biomass and productivity when the NPC was shifted poleward, and suggest that positioning influences advective transport of nutrients and perhaps key planktonic organisms from the sub-arctic domain thereby enhancing mid to upper trophic level species. This study is significant because climate change is predicted to cause poleward shifts in the westerlies that drive ocean currents and positioning of large marine gyre systems. Rather than reducing ecosystem productivity, poleward shifts in positioning of the NPC may be beneficial for many species of the central-northern CCE.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 95
    facet.materialart.
    Unknown
    The vertical distribution of cloud feedback in coupled ocean-atmosphere models (2011)
    Wiley
    Details
    Publication Date: 2011-06-28
    Description: We assess the vertical distribution of cloud feedbacks in coupled climate models, taking care to distinguish between cloud feedbacks and a change in cloud forcing. We show that the effect of cloud changes on the longwave fluxes provides a strong positive feedback that is broadly consistent across models. In contrast, the effect of cloud changes on the shortwave fluxes ranges from a modest negative to a strong positive feedback, and is responsible for most of the intermodel spread in net cloud feedback. The feedback from high clouds is positive in all models, and is consistent with that anticipated by the Proportionately Higher Anvil Temperature hypothesis over the tropics. In contrast, low cloud cover is responsible for roughly three-quarters of the difference in global mean net cloud feedback among models, with the largest contributions from regions associated with low-level subtropical marine cloud systems.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 96
    facet.materialart.
    Unknown
    The Greenland Sea Jet: A mechanism for wind-driven sea ice export through Fram Strait (2011)
    Wiley
    Details
    Publication Date: 2011-06-28
    Description: We present a mechanism for wind-driven sea ice export from the Arctic Ocean through Fram Strait for the period 1979–2007, using the output of a high-resolution regional atmospheric climate model. By explicitly calculating the components of the atmospheric momentum budget, we show that not large scale synoptic forcing (LSC), but mainly thermal wind forcing (THW) causes the persistent northerly jet (the Greenland Sea Jet) over Fram Strait. The jet results from horizontal temperature gradients in the atmospheric boundary layer (ABL), set up between cold ABL-air over the sea ice covered western Greenland Sea and the relatively warmer ABL over the ice-free eastern Greenland Sea. From 1993 onwards we find a negative trend in THW, due to a stronger response to climate warming of the ABL over the sea ice covered ocean, compared to that over the ice free ocean. Although on average LSC is smaller than THW, year to year variations in LSC explain most of the interannual variability in the sea ice area flux through Fram Strait (R = 0.81). A small positive trend is found for LSC, partly compensating the decrease in THW in recent years.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 97
    facet.materialart.
    Unknown
    Electrical properties of polycrystalline methane hydrate (2011)
    Wiley
    Details
    Publication Date: 2011-05-11
    Description: Electromagnetic (EM) remote-sensing techniques are demonstrated to be sensitive to gas hydrate concentration and distribution and complement other resource assessment techniques, particularly seismic methods. To fully utilize EM results requires knowledge of the electrical properties of individual phases and mixing relations, yet little is known about the electrical properties of gas hydrates. We developed a pressure cell to synthesize gas hydrate while simultaneously measuring in situ frequency-dependent electrical conductivity (σ). Synthesis of methane (CH4) hydrate was verified by thermal monitoring and by post run cryogenic scanning electron microscope imaging. Impedance spectra (20 Hz to 2 MHz) were collected before and after synthesis of polycrystalline CH4 hydrate from polycrystalline ice and used to calculate σ. We determined the σ of CH4 hydrate to be 5 × 10−5 S/m at 0°C with activation energy (Ea) of 30.6 kJ/mol (−15 to 15°C). After dissociation back into ice, σ measurements of samples increased by a factor of ∼4 and Ea increased by ∼50%, similar to the starting ice samples.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 98
    facet.materialart.
    Unknown
    A new model for the evolution of La Réunion volcanic complex from complete marine geophysical surveys (2011)
    Wiley
    Details
    Publication Date: 2011-05-11
    Description: Results from recent marine geophysical surveys offer a new perspective for characterizing the evolution processes of volcanic islands. In 2006, cruises FOREVER and ERODER 1 investigated the submarine flanks and the surrounding abyssal plain of La Réunion (Indian Ocean) to obtain for the first time a complete geophysical survey of the area. Combined analyses of these data reveal major differences in the evolution of the two emerged volcanoes, Piton des Neiges and Piton de la Fournaise. We show that debris avalanche deposits extend on the abyssal plain only offshore the active Piton de la Fournaise volcano attesting the occurrence of large flank-collapse events. The absence of such deposits offshore Piton des Neiges and the presence of compressive structures within the sedimentary unit below the edifice support a mechanism of slow deformation of this volcano, such as sliding or spreading. The slow deformation of Piton des Neiges has led to numerous secondary submarine slope instabilities and favored some unconfined turbidity flows which generated large sediment waves running downward all around the island. This study proposes a new model using the most complete marine data set available: slow deformation controls the evolution of Piton des Neiges whereas Piton de la Fournaise (formed on the flanks of a pre-existing edifice) experienced catastrophic, large flank-collapse events.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 99
    facet.materialart.
    Unknown
    Aerosol nucleation induced by a high energy particle beam (2011)
    Wiley
    Details
    Publication Date: 2011-05-12
    Description: We have studied sulfuric acid aerosol nucleation in an atmospheric pressure reaction chamber using a 580 MeV electron beam to ionize the volume of the reaction chamber. We find a clear contribution from ion-induced nucleation and consider this to be the first unambiguous observation of the ion-effect on aerosol nucleation using a particle beam under conditions that resemble the Earth's atmosphere. By comparison with ionization using a gamma source we further show that the nature of the ionizing particles is not important for the ion-induced component of the nucleation. This implies that inexpensive ionization sources - as opposed to expensive accelerator beams - can be used for investigations of ion-induced nucleation.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 100
    facet.materialart.
    Unknown
    Formation dynamics of subsurface hydrocarbon intrusions following the Deepwater Horizon blowout (2011)
    Wiley
    Details
    Publication Date: 2011-05-12
    Description: Hydrocarbons released following the Deepwater Horizon (DH) blowout were found in deep, subsurface horizontal intrusions, yet there has been little discussion about how these intrusions formed. We have combined measured (or estimated) observations from the DH release with empirical relationships developed from previous lab experiments to identify the mechanisms responsible for intrusion formation and to characterize the DH plume. Results indicate that the intrusions originate from a stratification-dominated multiphase plume characterized by multiple subsurface intrusions containing dissolved gas and oil along with small droplets of liquid oil. Unlike earlier lab measurements, where the potential density in ambient water decreased linearly with elevation, at the DH site it varied quadratically. We have modified our method for estimating intrusion elevation under these conditions and the resulting estimates agree with observations that the majority of the hydrocarbons were found between 800 and 1200 m.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...