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51.
A model for diurnal variations of neutral and ionic nitrogen compounds in the thermosphere is reconstructed on the basis of a new photochemical aspect on N(2D), together with new observations of the NO density. The NO density so far measured must be reduced by a factor 2, due to a revision of the fluorescence coefficient for the NO γ-band airglow. Incorporating the quenching reaction of N(2D) with O in the model calculation results in a reduction of the NO density at heights as low as 100 km. These two effects are combined to lead to an evaluation that the N(2D) quantum yield for various possible reactions is as large as 0.9. A smaller rate coefficient for the quenching reaction than that measured in the laboratory, i.e. 1.0 × 10?12cm3sec?1 is favourable for the recent NO observation in the early morning, as well as the observed emission rates of the 5200 A airglow from N(2D) The present model predicts a significant day-to-night variation of N and NO densities at heights above 100 km. Below 100 km, the NO density is fairly stable because of its long chemical time constant. Since the rate coefficient for the conversion of N(4S) to NO is highly temperature dependent, the relative population of N(4S) and NO is very sensitive to the thermospheric temperature variation. Large variations of both N(4S) and NO densities due to the temperature change could occur especially at night. The model is in good agreement with the NO observations so far available in low and middle latitudes, as well as the N observation by the use of a rocket in the twilight. 相似文献
52.
Direct measurements of the air-sea CO2 flux by the eddy covariance technique were carried out in the equatorial Indian Ocean. The turbulent flux observation system
was installed at the top of the foremast of the R/V MIRAI, thus minimizing dynamical and thermal effects of the ship body.
During the turbulent flux runs around the two stations, the vessel was steered into the wind at constant speed. The power
spectra of the temperature or water vapor density fluctuations followed the Kolmogorov −5/3 power law, although that of the
CO2 density fluctuation showed white noise in the high frequency range. However, the cospectrum of the vertical wind velocity
and CO2 density was well matched with those of the vertical velocity and temperature or water vapor density in this frequency range,
and the CO2 white noise did not influence the CO2 flux. The raw CO2 fluxes due to the turbulent transport showed a sink from the air to the ocean, and had almost the same value as the source
CO2 fluxes due to the mean vertical flow, corrected by the sensible and latent heat fluxes (called the Webb correction). The
total CO2 fluxes including the Webb correction terms showed a source from the ocean to the air, and were larger than the bulk CO2 fluxes estimated using the gas transfer velocity by mass balance techniques. 相似文献
53.
The ability of biodegradation for crude oil was examined for ten strains of marine bacteria. With regard to their degradation ability forn-alkanes the microorganisms tested could be divided into four groups, although the same result was not observed for microbial degradation of aromatic hydrocarbons obtained by the UV measurements. 相似文献
54.
Porosity strongly affects the overall ductile behavior of cohesive geomaterials undergoing plastic deformation. In the present paper, we proposed an original micromechanical approach that suitably couples Drucker–Prager‐type plasticity, evolving porosity under general triaxial loadings. The resulting model has the advantage to be based on a single macroscopic yield function, which also plays the role of plastic potential. It is shown that this yield function is particularly appropriate to account for the pore collapse and plastic shearing mechanisms that govern the mechanical behavior of the studied Lixhe chalk. Finally, the new model is implemented and validated by comparison to triaxial tests data, covering a wide range of confining pressures. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
55.
Ayako?ShinozakiEmail author Hisako?Hirai Hiroyuki?Kagi Tadashi?Kondo Taku?Okada Daisuke?Nishio-Hamane Shin-ichi?Machida Tetsuo?Irifune Takumi?Kikegawa Takehiko?Yagi 《Physics and Chemistry of Minerals》2012,39(2):123-129
High pressure and temperature reactions of a mixture of forsterite and hydrogen molecules have been carried out using a laser
heated diamond anvil cell at 9.8–13.2 GPa and ~1,000 K. In situ X-ray diffraction measurements showed no sign of decomposition
or phase transitions of the forsterite under these experimental conditions, indicating that the olivine structure was maintained
throughout all runs. However, a substantial expansion of the unit cell volume of the forsterite was observed for samples down
to ~3 GPa upon quenching to ambient pressure at room temperature. The Raman spectroscopy measurements under pressure showed
significant shifts of the Raman peaks of the Si–O vibration modes for forsterite and of the intramolecular vibration mode
for H2 molecules toward a lower frequency after heating. Additionally, no OH vibration modes were observed by Raman and FT-IR spectroscopic
measurements. These lines of evidence show that the observed volume expansion in forsterite is not explained by the incorporation
of hydrogen atoms as hydroxyl, but suggest the presence of hydrogen as molecules in the forsterite structure under these high
pressure and temperature conditions. 相似文献
56.
This article focuses on the dynamics of using numbers to construct an image of social reality in disaster areas. Numbers are
neither objective nor value-neutral but are rather generated, transmitted and shared with social signification. In other words,
numbers can be thought of as simply socially constructed information. Statistics and other numbers usually work in positive
ways. However, it is also possible that using numbers in the media can lead to unintended messages that could produce negative
consequences. We conducted field studies in disaster-stricken areas of the 2008 Wenchuan earthquake in China and compared
findings to the case of the 1995 Kobe earthquake in Japan in order to examine how numbers—in terms of the amount of donations,
the timeline of reconstruction projects and casualty figures—construct social reality and cause a variety of social dysfunctions. 相似文献
57.
Satoru Kojima Tamotsu Nozaki Hidehisa Nagata Ryota Tanahashi Ryoich Kondo Noriaki Okamura Kazuhiro Suzuki Akiko Ikeda Toshio Nakamura Tomoyuki Ohtani 《Environmental Earth Sciences》2014,71(6):2753-2763
Large-scale landslides along the Kubusu and Besso rivers in Toyama Prefecture are developed in the Miocene Iwaine Formation, which is composed of andesitic lava, tuff, and tuff breccia. In the middle member of this formation, the tuff is easily altered to montmorillonite-bearing rock, and subsequently plays an important role in the development of landslides events, which tend to be large-scale events, as the massive lava of the upper member forms a cap rock over the tuff. The Kiritani and Koinami basins, which are flat intermontane basins located along the Kubusu and Besso rivers, respectively, are interpreted as landslide-dammed lakes, later filled with sediment. Accelerator mass spectrometry 14C ages show that the landslides forming each dam occurred simultaneously, at approximately 2500 BP. These ages were measured from wood fragments embedded in the landslide material of Kiritani, and from an in situ stump drowned during the impoundment of Koinami. If the trigger of these landslides was an earthquake, it is most likely to have been the penultimate event along the Atotsugawa fault zone. 相似文献
58.
In order to provide a physical interpretation of the variation of the mechanical properties of Callovo-Oxfordian argillite with mineral composition, we implement three linear homogenization schemes. The argillite is modeled as a three phase material composed of a clay matrix and inclusions of quartz and calcite. It is shown that, unlike the dilute scheme and the self-consistent scheme, the Mori-Tanaka model describes the in situ experimental data well. The determined properties are finally used in a finite element computation. The aim is to evaluate the effect of mineral composition on the elastic response of the excavation of a vertical shaft in the context of the underground laboratory of Meuse/Haute Marne. 相似文献
59.
Christopher J. Norton Youichi Kondo Akira Ono Yingqi Zhang Mark C. Diab 《Quaternary International》2010,211(1-2):113-122
The nature of late Quaternary megafaunal extinctions has been the subject of intense debate since the 1960s. Traditionally, scientists cite either climatic changes or human predation as the primary reason for worldwide megafaunal extinctions. In many island cases (e.g., Madagascar, New Zealand), scientists have had a tendency to lean toward humans as being the direct or indirect dominant cause for the relatively quick extirpation of indigenous megafaunas. This study evaluates the record for megafaunal (e.g., Palaeoloxodon, Mammuthus, Sinomegaceros) extinctions in the Japanese islands and draw the tentative conclusion that: (1) humans directly and/or indirectly influenced the extinction of some large herbivores; and (2) the megafaunal extinctions likely began earlier than originally proposed; during the marine isotope stage (“MIS”) 3–2 transition (~30–20 ka) rather than during the MIS 2–1 (~15–10 ka) shift that roughly coincides with the advent of the Jomon period in Japan. However, we temper our findings due to the current paucity of sites in Japan that have associated archaeology and vertebrate paleontological materials that date to the MIS 3–2 transition. 相似文献
60.
In this paper, we focus on strength properties of double porous materials having a Drucker-Prager solid phase at microscale. The porosity consists in two populations of micropores and mesopores saturated with different pressures. To this end, we consider a hollow sphere subjected to a uniform strain rate boundary conditions. For the microscale to mesoscale transition, we take advantage of available results by Maghous et al. (2009), while the meso to macro upscaling is performed by implementing a kinematical limit analysis approach using Eshelby-like trial velocity fields. This two-step homogenization procedure delivers analytical expression of the macroscopic criterion for the considered class of saturated double porous media. This generalizes and improves previous results established by Shen et al. (2014). The results are discussed in terms of the existence or not of effective stresses. Some illustrations are provided. 相似文献