Composition and pressure dependence of lattice thermal conductivity of (Mg,Fe)O solid solutions     

Akira Hasegawa  Kenji Ohta  Takashi Yagi  Kei Hirose  Yoshiyuki Okuda  Tadashi Kondo 《Comptes Rendus Geoscience》2019,351(2-3):229-235

We measured the lattice thermal conductivities of Fe_0.98O wüstite and iron-rich (Mg,Fe)O magnesiowüstite using the pulsed light heating thermoreflectance technique with a diamond anvil cell up to 61 GPa at 300 K. We found that the thermal conductivity of wüstite does not show a monotonic increase as a function of pressure, contrary to that of MgO periclase. Rocksalt (B1) to rhombohedral B1 transition is likely to induce an abnormal pressure response in the conductivity of wüstite. Our results also show that magnesiowüstite has a lower conductivity than that of MgO and FeO endmembers due to a strong iron impurity effect, which is well reproduced by a model considering phonon-impurity scattering in a binary solid solution.  相似文献   

Canopy conductance in a two‐storey Siberian boreal larch forest,Russia          下载免费PDF全文

Bao‐Lin Xue  Zhanling Li  Xin‐An Yin  Tieliang Zhang  Shin'ichi Iida  Kyoichi Otsuki  Takeshi Ohta  Qinghua Guo 《水文研究》2015,29(6):1017-1026

A larch forest in eastern Siberia was characterized by the presence of two distinct storeys, the overstorey with a small leaf area index (LAI) and a dense understorey with a relatively large LAI. To understand the roles of the overstorey and understorey in forest–atmosphere water exchange, canopy conductance (G_c), a critical parameter used in determining the energy and mass exchange, was calculated on the basis of latent heat flux above the overstorey and understorey, measured separately. Results showed that G_c for the overstorey (G_co) and understorey (G_cu) experienced different seasonal fluctuations. G_co was smaller than G_cu during periods of leaf expansion and leaf fall and showed an increasing trend until 1 month after the onset of leaf expansion. In contrast, a sharp decrease in G_co was observed immediately before onset of leaf fall. Furthermore, G_co was slightly larger than G_cu during the fully foliated period. A simple model using solar radiation and vapour pressure deficit (D) as inputs successfully reproduced the G_c in fully foliated periods with acceptable accuracy. Furthermore, both the understorey and overstorey in this study have a large reference G_c (G_c at D = 1 KPa) than their counterparts of other boreal forests and would not be able to sustain a constant leaf–soil water potential difference as D increases. We speculated that this confers the forest with an advantage allowing it to be able to sustain carbon assimilation during large D days and thus provides for the survival of the ecosystem during the short growing season at this site. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Accurate ocean tide modeling in southeast Alaska and large tidal dissipation around Glacier Bay     

Daisuke Inazu  Tadahiro Sato  Satoshi Miura  Yusaku Ohta  Kazuyuki Nakamura  Hiromi Fujimoto  Christopher F. Larsen  Tomoyuki Higuchi 《Journal of Oceanography》2009,65(3):335-347

An accurate prediction of ocean tides in southeast Alaska is developed using a regional, barotropic ocean model with a finite difference scheme. The model skill is verified by the observational tidal harmonics in southeast Alaska including Glacier Bay. The result is particularly improved in Glacier Bay compared to the previous model described by Foreman et al. (2000). The model bathymetry dominates the model skill. We re-estimate tidal energy dissipation in the Alaska Panhandle and suggest a value for tidal energy dissipation of 3.4 GW associated with the M₂ constituent which is 1.5 times the estimation of Foreman et al. (2000). A large portion of the M₂ energy budget entering through Chatham Strait is dissipated in the vicinity of Glacier Bay. Moreover, it is shown that the developed model has the potential to correct the ocean tide loading effect in geodetic data more efficiently than the model of Foreman et al. (2000), especially around Glacier Bay.  相似文献   

Theoretical Evaluation of the Mechanical Behavior of Unsaturated Soils     

Michinori Honda  Shintaro Ohno  Atsushi Iizuka  Katsuyuki Kawai  Hideki Ohta 《Geotechnical and Geological Engineering》2011,29(2):171-180

An evaluation method for the mechanical behavior of unsaturated soils is studied in this paper. Although the mechanical behavior of unsaturated soils is complicated, a simple modeling is preferable in practice. This is because the soil properties are not homogeneous and ground data is limited when structures are being designed. In addition, in order to evaluate the reliability of the design, the physical meanings of the parameters applied in the prediction model should be clear. Firstly, the authors study the relationship between compaction curves and compression indexes in the unsaturated state that is used in the proposed constitutive model. Based on the constitutive model, the stress paths for constant volume shear tests are formulated under a constant void ratio condition and the stress paths for undrained shear tests are calculated under a constant water content condition. In the case of unsaturated specimens, the volume of these specimens changes with the shear deformation and the stress paths depend on the initial degree of saturation. The results of the calculation qualitatively describe the test results by considering the changes in effective confining pressure in the undrained condition and the water retention curves.  相似文献   

Analysis of the geographical accessibility of neurosurgical emergency hospitals in Sapporo city using GIS and AHP     

K. Ohta  S. Takano  S. Kagaya  H. Yamada  H. Minakami 《International journal of geographical information science》2013,27(6):687-698

To improve the geographical accessibility of neurosurgical emergency hospitals for elderly people, we developed several alternative site plans for a new neurosurgical emergency hospital in Sapporo, Japan. Hospitals, population data, routes, and the numerical information for the Analytic Hierarchy Process computations were input into a Geographical Information System. Pairwise comparison revealed the following weights which were assigned to each of the four criteria: 0.674 for availability of hospital beds; 0.169 for the maximum road distance of the shortest routes; 0.101 for the elderly population within a 3‐km radius; and 0.056 for the median road distance of the shortest routes. The alternative proposed could cover 4000 more elderly people in the 3‐km radius of the hospitals. The integration of Geographical Information Systems and the Analytic Hierarchy Process constitutes a powerful tool for analysing traffic conditions in mid‐sized cities and for suggesting city planning to improve prognosis of stroke.  相似文献   

Gravity measurements with a portable absolute gravimeter A10 in Syowa Station and Langhovde,East Antarctica     

Takahito Kazama  Hideaki Hayakawa  Toshihiro Higashi  Shingo Ohsono  Shunsuke Iwanami  Tomoko Hanyu  Harumi Ohta  Koichiro Doi  Yuichi Aoyama  Yoichi Fukuda  Jun Nishijima  Kazuo Shibuya 《Polar Science》2013,7(3-4):260-277

Absolute gravity values were measured with a portable absolute gravimeter A10 in East Antarctica, for the first time by the Japanese Antarctic Research Expedition. This study aims to investigate regional spatiotemporal variations of ice mass distributions and associated crustal deformations around Syowa Station by means of repeated absolute gravity measurements, and we obtained the first absolute gravity value in Southern Langhovde on the Antarctic Continent. The average absolute gravity value at the newly installed benchmark AGS01 in Langhovde (obtained on 3 February 2012) was 982535584.2 ± 0.7 μgal (1 [μgal] = 1 × 10^?8 [m/s²]), which was in agreement with the gravity values obtained by the past relative gravity measurements within 1 mgal. In addition, the average absolute gravity value obtained at AGSaux in Syowa Station was consistent with both previous absolute gravity values and those obtained by simultaneous measurements using an FG5 gravimeter, owing to adequate data corrections associated with tidal effects and time variations in atomic clock frequencies. In order to detect the gravity changes associated with the ice mass changes and other tectonic phenomena, we plan to conduct absolute gravity measurements at AGS01 again and at other campaign sites around Syowa Station as well in the near future, with careful attention paid to the impacts of severe environmental conditions in Antarctica on gravity data collection.  相似文献   

A Subaru/Suprime-Cam wide-field survey of globular cluster populations around M87 – II. Colour and spatial distribution     

Naoyuki Tamura †  Ray M. Sharples  Nobuo Arimoto  Masato Onodera  Kouji Ohta  Yoshihiko Yamada 《Monthly notices of the Royal Astronomical Society》2006,373(2):601-612

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Supermassive black hole mass functions at intermediate redshifts from spheroid and AGN luminosity functions     

Naoyuki Tamura  Kouji Ohta  Yoshihiro Ueda 《Monthly notices of the Royal Astronomical Society》2006,365(1):134-146

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A submillimetre survey of Lyman α haloes in the SA 22 protocluster at z= 3.1     

J. E. Geach  Y. Matsuda  Ian Smail  S. C. Chapman  T. Yamada  R. J. Ivison  T. Hayashino  K. Ohta  Y. Shioya  Y. Taniguchi 《Monthly notices of the Royal Astronomical Society》2005,363(4):1398-1408

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Estimation of spectral refractive index of colloidal sulfur at 20°C     

Tsuyoshi Samukawa  Masamitsu Onitsuka  Kazuyuki Ohta  Mamoru Tominaga  Hidenori Yoshiyama 《Journal of Oceanography》1992,48(2):129-138

In the marine environment, colloidal sulfurs often occur due to the redox reaction of sulfide ions and oxygen molecules. It is important to know the spectral refractive index of colloidal sulfurs for the discussion of the light scattering in the region where colloidal sulfurs are formed. We presented new methods to estimate the refractive index from the wave length of maximum absorbance (turbidity) of a nearly mono-dispersed colloidal solution. In these methods, the ripples in a first main maximum of the scattering efficiency,Q _sca , were taken into consideration. By virtue of these methods, we obtained the spectral refractive index of colloidal sulfurs,m _s (), at 20°C. The Cauchy's expression of it was given by

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