共查询到20条相似文献,搜索用时 406 毫秒
1.
P. Mogilevsky 《Physics and Chemistry of Minerals》2007,34(3):201-214
The regular solid solution model has been applied to solid solubility in the monazite–xenotime systems and is verified against
the available experimental data for LaPO4–YPO4 and CePO4–YPO4 systems. The model is then used to predict the miscibility gaps in a number of other monazite–xenotime systems. The implications
for prospective two-phase monazite–xenotime fiber coatings for applications in ceramic matrix composites (CMCs) are discussed.
相似文献
P. MogilevskyEmail: |
2.
Boris Kolesov 《Physics and Chemistry of Minerals》2008,35(5):271-278
Single-crystal polarized Raman spectra (3,000–4,000 cm−1 at 3 ≤ T ≤ 300 K) were measured for synthetic alkali-free and natural beryl, Be2Al3Si6O18·xH2O, to determine the behavior of H2O molecules of both Type I and Type II in the cavities. At low temperature, the H2O molecules of Type I displace from the center of cavity and give rise to very weak hydrogen bonding with the host lattice.
The H2O Type I translational motion is characterized by substantial anharmonicity and looks like a motion of “a particle in the
box” with a frequency of 6.3 cm−1. Water Type II is characterized by a free rotation with respect to the C
2 molecule axis, and it makes possible the water nuclear isomers (i.e. ortho- and para-) to be observed at low temperature.
相似文献
Boris KolesovEmail: |
3.
Dmitry L. Lakshtanov Stanislav V. Sinogeikin Jay D. Bass 《Physics and Chemistry of Minerals》2007,34(1):11-22
The single-crystal acoustic velocities of α- and β-quartz were measured by Brillouin spectroscopy to a maximum temperature
>1,500°C at room pressure. From these velocities, the single-crystal elastic moduli were calculated up to 1,050°C, exceeding
the temperature range of previous measurements by 350°C for the elastic moduli and by 710°C for acoustic velocities. The ordinary
refractive index (n
o) of α- and β-quartz was measured from room temperature to 800°C. In the temperature interval from ∼950 to 1,000°C a subtle
change in the temperature derivative of the longitudinal acoustic velocity was observed in platelet geometry for all measured
directions. The high-temperature acoustic velocity data may indicate the presence of a second phase, presumably β-cristobalite,
that nucleates below 1,000°C.
相似文献
Dmitry L. LakshtanovEmail: |
4.
Giorgio Hadi Curti 《GeoJournal》2009,74(3):201-208
Ostensibly, subtitles in films serve as linguistic approximations of meaning. Expectedly then, much of the debate surrounding
subtitling has been concerned with representational accuracy, fidelity and authenticity. In this article I argue that by encountering
subtitles as affective bodily expressions, as opposed to approximate representations of pre-existent meanings or intentions,
filmic experiences may be(come) transformed and differently transformational. As a result, meaning and accuracy in subtitles
as superimposed signifiers or static representations become secondary to subtitles as spatially affective- and expressive-movements
intimately part of filmic scapes. The creative use of subtitling in Bekmambetov’s Russian language film Night Watch (Nochnoy dozor; 2006 [2004]) is discussed.
相似文献
Giorgio Hadi CurtiEmail: |
5.
J. A. L. Rabone A. Carter A. J. Hurford N. H. de Leeuw 《Physics and Chemistry of Minerals》2008,35(10):583-596
We introduce a simple method to simulate the “ion explosion spike” mechanism of fission track formation within the framework
of classical molecular dynamics. The method is applied to six apatite compositions and the resulting tracks are compared with
each other as well as with the damage produced by another mechanism—the “Displacement spike”. In contrast to experimentally
observed tracks, the radii of simulated tracks are not dependent on their direction in the crystal. Since the simulations
model accurately the elastic response of apatites, this suggests that the experimentally observed difference in track radii
for tracks along different crystal directions is not entirely caused by anisotropy in the elasticity of apatite. We suggest
that anisotropy in the interactions between the electric fields of fission fragments and the crystal ions is a major factor
in the final radii of fission tracks. In fluorapatite, the simulations also reveal the formation of small clusters of fluorite-like
material in the core of the fission track, a phenomenon which has yet to be confirmed experimentally.
相似文献
J. A. L. RaboneEmail: |
6.
Melt inclusion formation mechanisms and compositional effects in high-An feldspar and high-Fo olivine in anhydrous mafic silicate liquids 总被引:1,自引:1,他引:0
Important aspects of melt inclusion formation and potential compositions effects have been addressed through a series of experiments using anorthite/fosterite saturated anhydrous mafic liquids. Experimental charges were cooled from 1,300 to 1,230 and 1,210°C at rates of 1–10°/min followed by 0–24 h isothermal periods. Hopper and skeletal crystal morphologies with variable degrees of completeness developed during the cooling period. Planar overgrowth of these textures during isothermal periods led to the formation of inclusions, the majority of which formed after 6 h of isothermal run time. We suggest that the change in morphologies is related to a decrease in growth rates and changes in dominant growth mechanisms. In general, inclusion compositions were uniform and similar to the host glass, indicating that with the isothermal times required for most inclusions to form, a boundary layer was not entrapped that could be detected within the limits of our analyses.
相似文献
Edward KohutEmail: Phone: +1-541-7373023Fax: +1-541-7371200 |
Roger L. NielsenEmail: Phone: +1-541-7371235 |
7.
Dorian Speakman 《Natural Hazards》2008,44(1):111-127
A vulnerability index for the Fire Service in the UK has been designed to identify vulnerable locations during episodes of
severe floods. Taking recent case studies with the UK Fire Service, the patterns of vulnerability, in terms of demand on time
and resources, can be explained by investigating the environmental causes and their interaction with the adaptive capacity
of the response agencies.
相似文献
Dorian SpeakmanEmail: |
8.
Said Ettazarini 《Environmental Geology》2006,50(6):919-929
This study takes the groundwater of the Moroccan limestone aquifer of Oum Er-Rabia as an example of statistical and cartographical approaches in water resources management. Statistical analyses based on frequency distribution and PCA methods revealed the homogeneity of waters with the existence of abnormal points and have helped to assess correlations between the studied variables. The mapping approach illustrated that waters are influenced by the lithology of the surrounding rocks and are of Ca–Mg–HCO3, Ca–Mg–Cl–SO4, and mixed types according to the Piper classification. The quality of water is of high to medium, north of the basin, but it is of medium to bad, NE and south, due to excessive contents of chloride, sulfate and nitrate. According to the US Salinity Laboratory classification, water used for irrigation in the eastern and the southern parts of the basin should take into consideration the drainage conditions, the nature of plants and the addition of gypsum doses.
相似文献
Said EttazariniEmail: Phone: +212-66-407610 |
9.
Using density functional simulations, within the generalized gradient approximation and projector-augmented wave method, we study structures and energetics of CaSiO3 perovskite in the pressure range of the Earths lower mantle (0–150 GPa). At zero Kelvin temperature the cubic
CaSiO3 perovskite structure is unstable in the whole pressure range, at low pressures the orthorhombic (Pnam) structure is preferred. At 14.2 GPa there is a phase transition to the tetragonal (I4/mcm) phase. The CaIrO3-type structure is not stable for CaSiO3. Our results also rule out the possibility of decomposition into oxides.
相似文献
Daniel Y. JungEmail: Phone: +41-44-6323744Fax: +41-44-6321133 |
10.
Spatial and temporal knowledge representation 总被引:1,自引:1,他引:0
Antony Galton 《Earth Science Informatics》2009,2(3):169-187
Knowledge Representation (KR) originated as a discipline within Artificial Intelligence, and is concerned with the representation
of knowledge in symbolic form so that it can be stored and manipulated on a computer. This article surveys that part of KR
that is concerned with the representation of space and time, with particular reference to the use of such representations
in geographical information science.
相似文献
Antony GaltonEmail: |
11.
G. Ottonello B. Civalleri J. Ganguly M. Vetuschi Zuccolini Y. Noel 《Physics and Chemistry of Minerals》2009,36(2):87-106
Thermophysical properties of the various polymorphs (i.e. α-, β- and γ) of Mg2SiO4 were computed with the CRYSTAL06 code within the framework of CO-LCAO-GTF approach by using the hybrid B3LYP density functional
method. Potential wells were calculated through a symmetry preserving, variable cell-shape structure relaxation procedure.
Vibrational frequencies were computed at the long-wavelength limit corresponding to the center of the Brillouin zone (k → 0). Thermodynamic properties were estimated through a semiclassical approach that combines B3LYP vibrational frequencies
for optic modes and the Kieffer’s model for the dispersion relation of acoustic modes. All computed values except volume (i.e.
electronic energy, zero point energy, optical vibrational modes, thermal corrections to internal energy, standard state enthalpy
and Gibbs free energy of reaction, bulk modulus and its P and T derivatives, entropy, C
V, C
P) are consistent with available experimental data and/or reasonable estimates. Volumes are slightly overestimated relative
to those determined directly by X-ray diffraction. A set of optimized volumetric properties that are consistent with the other
semiclassical properties of the phases α, β and γ have been derived by optimization procedure such that the calculated boundaries
for the α/β and β/γ equilibria have the best overall agreement with the experimental data for these transitions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
G. OttonelloEmail: |
12.
Igor Vojnovic 《GeoJournal》2007,69(4):271-300
Throughout the 20th century, government in the U.S. has gone through significant changes; initially responding to the disorder
of early capitalism, and later, to the economic crisis of the 1970s. This article will explore the changes in the U.S. political
landscape over the last century, as well as the recent rise of neo-liberalism. In addition, with the analysis of the model
laissez-faire municipal government, the City of Houston, the article will illustrate how the basic weaknesses of neoliberalism
at the national level are also evident at the local scale of government.
相似文献
Igor VojnovicEmail: |
13.
Space Physics Interactive Data Resource—SPIDR 总被引:1,自引:0,他引:1
Mikhail Zhizhin Eric Kihn Rob Redmon Dmitry Medvedev Dmitry Mishin 《Earth Science Informatics》2008,1(2):79-91
SPIDR (Space Physics Interactive Data Resource) is a standard data source for solar-terrestrial physics, functioning within
the framework of the ICSU World Data Centers. It is a distributed database and application server network, built to select,
visualize and model historical space weather data distributed across the Internet. SPIDR can work as a fully-functional web-application
(portal) or as a grid of web-services, providing functions for other applications to access its data holdings.
相似文献
Mikhail ZhizhinEmail: |
14.
Modeling stream-aquifer interactions in a shallow aquifer, Choele Choel Island, Patagonia, Argentina 总被引:3,自引:1,他引:2
A groundwater/surface-water interaction model was developed for the shallow alluvial aquifer of the Choele Choel Island in
Patagonia, Argentina. In this semiarid climate, agriculture is sustained by an irrigation/drainage system. During the irrigation
season, seepage losses through unlined distribution canals in irrigated fields contribute to elevated groundwater levels,
jeopardizing fruit productivity in some areas. Moreover, high stream stages during the irrigation season interfere with groundwater
drainage. The model utilized MODFLOW and its stream package, and was successfully calibrated for a historical irrigation season.
Modeling results indicate that drainage through streams is significantly higher than drainage through artificial drains. The
stream/aquifer relationship proved very responsive to water table rises caused by irrigation. This response manifested as
changes in the gaining/losing character of stream reaches. A synthetic run aimed at isolating the effect of streamflow changes
on groundwater levels showed that the effect of higher streamflows dissipates toward the interior of the island, disappearing
completely at the island center. Even though some results were qualitative, the model helped to provide a better understanding
of the coupled system to elucidate some of the causes of a rising water table on the island.
相似文献
Leticia B. RodríguezEmail: |
15.
This paper describes an application of the geographic information system (GIS) technology to a ground stability assessment
in the karst area of Dzerzhinsk, Russia. In the stability analysis, the groundwater level changes in the karst aquifer could
cause suffosion sinkholes when the gravitational force was greater than the soil strength. The GIS technology was used to
combine various data and to delineate the zones of potential gravitational collapse and suffosion collapse in the area.
相似文献
V. V. TolmachevEmail: |
16.
Anthony John Christopher 《GeoJournal》2006,67(2):123-136
The pattern of Church of England dioceses has evolved over a period of 1,400 years. It reflects the practical response of
the Church to the changing political and demographic patterns of the country. No ideal size and form of diocese was ever devised
and few systematic attempts were made to achieve a degree of equity between them. The constitutional link between state and
church has inhibited change for the last 80 years, although society has changed significantly. Nevertheless, rapid constitutional
reforms, especially in the House of Lords, may be reflected in ecclesiastical reorganisation of the dioceses.
相似文献
Anthony John ChristopherEmail: |
17.
The aim of this paper is to use an economic framework to derive decision making rules for river basin management with a focus on groundwater resources. Using an example from northern Nigeria, the paper provides an example of how decision making for sustainable water resources management may be facilitated by comparing net benefits and costs across a river basin. It is argued that economic tools can be used to assess the value of water resources in different uses, identify and analyze management scenarios, and provide decision rules for the sustainable use and management of surface and ground water resources in the region.
相似文献
Gayatri AcharyaEmail: |
18.
Catherine Hesse-Swain 《GeoJournal》2006,66(3):257-272
People living in the northeast of Thailand interchangeably label themselves and are labelled by others as Isan, Thai Isan,
Lao Isan, Thai or Lao, depending on the ethnic, political, social or familial nuances of any given situation. I use the term
Lao Isan to refer specifically to Isan people of Lao origin or ethnicity. Lao Isan are subject to complex and often competing notions
of Isan-ness, Lao-ness and Thai-ness by insiders and outsiders. Using data derived from an ethnographic study of popular Thai television and Lao Isan youth (aged
17–25) living in the city of Khon Kaen and the town of Mahasarakham in northeast Thailand in 2002, this paper explores contemporary
and co-existing interpretations of Isan identity or Khwampenisan among Lao Isan youth in relation to self-image and connections with national understandings of physical beauty as they are
perpetuated in Thai-produced television programs.
相似文献
Catherine Hesse-SwainEmail: |
19.
The irreversible water–rock mass exchanges leading to the production of the Fiume Grande valley (Calabria, Italy) stream waters
and groundwaters, starting from local rainwaters, were simulated through reaction path modeling in reaction progress (stoichiometric)
mode. The simulations assumed bulk dissolution of a phyllitic rock and calcite and precipitation of gibbsite, kaolinite, amorphous
silica, illite, a smectite solid mixture, a hydroxide solid mixture, and a trigonal carbonate solid mixture. The analytical
contents of major and trace elements in stream waters and groundwaters were satisfactorily reproduced. However, further investigations
are necessary to clarify the fate of As in this natural systems.
相似文献
Rosanna De RosaEmail: |
20.
In a media saturated world of globalization, information flow and knowledge economies, an interesting paradox exists: geographic
literacy appears to be on the decline while geographic information is on the rise. In this introduction to a collection of
essays on geographies of the media, we explore this paradox and use Baudrillard’s (1994) work on Simulacra and Simulation to argue that increased mediated information does not produce more meaning, but rather leads to a catastrophe of meaning
and the medium. Drawing from McLuhan’s axiom, “the medium is the message,” we posit that with more mediated information there
is less meaningful information and as such we need to address geographic media literacy as a primary mode through which to
address geographic literacy.
相似文献
Jim CraineEmail: |