基于Logit 模型的世界主要作物播种面积变化模拟   总被引：6，自引：1，他引：5  

吴文斌  杨鹏  谈国新  邹金秋  柴崎亮介  唐华俊 《地理学报》2007,62(6):589-598

农作物播种面积动态变化因其重要性已经引起了国内外学者的广泛关注。从“人-地 关系”中人的角度出发, 利用多元Logit 模型初步建立了全球尺度的农作物播种面积变化模 拟系统, 分析研究了未来30 年内世界主要农作物播种面积变化的数量特征和空间格局。模型建立思路是: 作物播种面积变化是农户作物选择行为的直接结果, 而选择何种作物进行播种是由作物效用决定的。因此, 利用离散选择理论, 选择影响作物效用大小的主要解释变量建立效用函数, 动态模拟农户作物选择行为, 并得到这种选择行为所带来的农作物播种面积变 化的时空特征。模型建立后, 利用联合国粮农组织(FAO) 2001-2003 年统计数据和2001 年MODIS 全球土地覆盖数据产品对模型结果进行验证, 结果表明模型运行可靠, 和实际状况吻合较好, 可以应用于未来情景模拟分析。其后, 以5 年为步长, 模型对世界四大作物(水稻、玉米、小麦和大豆) 在2005-2035 年间的播种面积动态变化进行了模拟, 从全球作物总播种面 积变化差异、四大作物播种面积变化的区域差异和不同区域内四大作物播种面积变化差异等方面进行了分析研究, 结果表明: 不同作物播种面积变化的数量特征和空间格局是不相同的。 虽然目前模型还存在一些不确定性, 但仍然能够在一定程度上为理解现在和未来农业土地利用的复杂动态变化提供帮助, 模拟结果可为有关部门提供决策支持和信息服务。  相似文献   

Experimental investigation on cohesionless sandy bank failure resulting from water level rising   总被引：1，自引：1，他引：0  

Ryosuke Arai  Kazuyuki Ota  Takahiro Sato  Yasushi Toyoda 《国际泥沙研究》2018,33(1):47-56

In the last decade, sediment replenishment forming cohesionless sandy banks below dams has become an increasingly common practice in Japan to compensate for sediment deficits downstream. The erosion process of the placed cohesionless sediment is a combination of lateral toe-erosion and the following mass failure. To explore cohesionless bank failure mechanisms, a series of experiments was done in a soil tank using a compacted sandy soil mass exposed to an increasing water level. Two types of uniform sand(D_(50) = 0.40 mm and 0.17 mm) and two bank heights(50 cm and 25 cm) were used under the condition of a constant bank slope of 75°. The three dimensional(3D) geometry of the bank after failure was measured using a handheld 3D scanner. The motion of bank failure was captured using the particle image velocimetry(PIV) technique, and the matric suction was measured by tensiometers. The compacted sandy soil was eroded by loss of matric suction accompanying the rise in water level which subsequently caused rotational slide and cantilever toppling failure due to destabilization of the bank. The effect of erosion protection resulting from the slumped blocks after these failures is discussed in the light of different failure mechanisms. Tensile strength is analyzed by inverse calculation of cantilever toppling failure events. The tensile strength had non-linear relation with degree of saturation and showed a peak.The findings of the study show that it is important to incorporate the non-linear relation of tensile strength into stability analysis of cantilever toppling failure and prediction of tension crack depth within unsaturated cohesionless banks.  相似文献   

Shape detection of multiple subsurface cavities by particle filtering with elastic wave propagation     

Ryosuke Takamatsu  Kazunori Fujisawa  Kazuyuki Nakahata  Akira Murakami 《国际地质力学数值与分析法杂志》2020,44(15):2025-2041

A numerical technique for detecting the number and shape of subsurface cavities is presented, applying the particle filter and the parametric level set method to elastic wave propagation under the ground. When subsurface cavities exist, the elastic wave propagating in the ground is reflected at the boundary faces of the cavities. Observing the velocity of the reflection wave at the surface of a ground that includes multiple cavities and parameterizing the shape of the cavities by the parametric level function, both the number and the shape of the cavities can be identified by the particle filter. Numerical experimentation for detecting multiple cavities is conducted with synthetic observation data. The results show that the proposed technique enables the number of cavities to be identified by the number of peaks in the posterior probabilistic distribution function and solves geometric inverse problems by estimating the shape of the cavities through the parameter identification of the level set function.  相似文献   

Evaluation of slope stability by finite element method using observed displacement of landslide   总被引：1，自引：0，他引：1  

Yasuo Ishii  Keiichi Ota  Senro Kuraoka  Ryosuke Tsunaki 《Landslides》2012,9(3):335-348

To monitor land deformation in detail, we ran a large-scale field test in which an artificial landslide was induced by the application of a load to a natural slope. The measured landslide displacement was reproduced numerically through the use of finite element model analysis with a two-dimensional elasto-viscoplastic model. The analysis suggested that the strength of the sliding surface decreased as the landslide mass moved. We propose a simple method for estimating safety factors. The method involves back-calculation of shear strength parameters through reproduction of observed landslide displacements and calculating the ratio of driving force to resisting force acting on the sliding surface as modeled by joint elements. This ratio, the “stability index”, shows the same trend as safety factors calculated by a two-dimensional limit equilibrium method and a shear strength reduction method that use back-calculated shear strength parameters estimated from the limit equilibrium state. The results indicate that the stability index may be applicable to the assessment of slope stability.  相似文献   

Marine artificial structures as amplifiers of Aurelia aurita s.l. blooms: a case study of a newly installed floating pier     

Ryosuke Makabe  Ryuji Furukawa  Mariko Takao  Shin-ichi Uye 《Journal of Oceanography》2014,70(5):447-455

Increase of marine artificial structures, providing more substrate for jellyfish polyps, has been argued to increase jellyfish outbreaks, although no explicit evidence exists. We report a case study demonstrating a remarkable increase of Aurelia aurita s.l. ephyrae after the installation of a floating pier (48 × 6 m) in a fishing port on the Inland Sea of Japan. Monitoring of ephyrae from January 2010, prior to the installation of the floating pier in April 2010, to July 2011, revealed that their time-weighted average density increased 3.5 fold, from 1.1 to 3.9 ephyrae m^?3, and the integrated number of ephyrae exported from the port increased 4.3 fold, from 5.7 × 10⁶ to 25 × 10⁶ ephyrae, after the installation. However, in a nearby port, a control site, the abundance of ephyrae decreased by ca. one third during the same period. Monitoring of polyps showed that they initially colonized the undersurface of the pier by August 2010, followed by a rapid population increase. They strobilated from December 2010 to May 2011. We computed the number of ephyrae released from the strobilae to be ca. 25 × 10⁶, very close to the net increase of ephyrae produced and exported from the port. This study corroborates that the installation of an artificial structure provides new a substrate for polyps, which allows them to produce more ephyrae to induce medusa blooms.  相似文献   

Crystal chemistry of Fe3+-bearing (Mg,Fe)SiO3 perovskite: a single-crystal X-ray diffraction study     

Ryosuke Sinmyo  Elena Bykova  Catherine McCammon  Ilya Kupenko  Vasily Potapkin  Leonid Dubrovinsky 《Physics and Chemistry of Minerals》2014,41(6):409-417

Magnesium silicate perovskite is the predominant phase in the Earth’s lower mantle, and it is well known that incorporation of iron has a strong effect on its crystal structure and physical properties. To constrain the crystal chemistry of (Mg, Fe)SiO₃ perovskite more accurately, we synthesized single crystals of Mg_0.946(17)Fe_0.056(12)Si_0.997(16)O₃ perovskite at 26 GPa and 2,073 K using a multianvil press and investigated its crystal structure, oxidation state and iron-site occupancy using single-crystal X-ray diffraction and energy-domain Synchrotron Mössbauer Source spectroscopy. Single-crystal refinements indicate that all iron (Fe²⁺ and Fe³⁺) substitutes on the A-site only, where \( {\text{Fe}}^{ 3+ } /\Upsigma {\text{Fe}}\sim 20\,\% \) based on Mössbauer spectroscopy. Charge balance likely occurs through a small number of cation vacancies on either the A- or the B-site. The octahedral tilt angle (Φ) calculated for our sample from the refined atomic coordinates is 20.3°, which is 2° higher than the value calculated from the unit-cell parameters (a = 4.7877 Å, b = 4.9480 Å, c = 6.915 Å) which assumes undistorted octahedra. A compilation of all available single-crystal data (atomic coordinates) for (Mg, Fe)(Si, Al)O₃ perovskite from the literature shows a smooth increase of Φ with composition that is independent of the nature of cation substitution (e.g., \( {\text{Mg}}^{ 2+ } - {\text{Fe}}^{ 2+ } \) or \( {\text{Mg}}^{ 2+ } {\text{Si}}^{ 4+ } - {\text{Fe}}^{ 3+ } {\text{Al}}^{ 3+ } \) substitution mechanism), contrary to previous observations based on unit-cell parameter calculations.  相似文献   

Spore-forming halophilic bacteria isolated from Arctic terrains: Implications for long-range transportation of microorganisms     

Kise Yukimura  Ryosuke Nakai  Shiro Kohshima  Jun Uetake  Hiroshi Kanda  Takeshi Naganuma 《Polar Science》2009,3(3):163-169

Organisms living in the Arctic terrains such as Greenland have to deal with low temperature conditions. The mechanisms by which bacteria resist to low temperature are largely unknown; however, a well-known survival strategy of the microorganisms inhabiting the Arctic is spore forming. Moreover, halophilic bacteria are often resistant to various stresses. We have attempted isolation of spore-forming halophilic bacteria from Arctic terrains. We isolated 10 strains of spore-forming halophilic bacteria from the samples collected from a glacial moraine in Qaanaaq, Greenland in July 2007. Identification based on 16S rRNA gene sequence similarities showed that the isolates were closely related to the Oceanobacillus, Ornithinibacillus, Virgibacillus, Gracilibacillus, and Bacillus genera. In addition, the 16S rRNA sequences of some isolates were extremely similar to those of strains from the desert sand in China (100% identity, near full length), the source of the so-called “yellow dust.” Previous research indicated that yellow dust had been transported to Greenland by the wind. Our research implies the long-range transportation of these microorganisms to locations such as the Arctic.  相似文献   

Electrical conductivity of NaCl-bearing aqueous fluids to 600 °C and 1 GPa     

Ryosuke?Sinmyo  Hans?KepplerEmail author 《Contributions to Mineralogy and Petrology》2017,172(1):4

The electrical conductivity of aqueous fluids containing 0.01, 0.1, and 1 M NaCl was measured in an externally heated diamond cell to 600 °C and 1 GPa. These measurements therefore more than double the pressure range of previous data and extend it to higher NaCl concentrations relevant for crustal and mantle fluids. Electrical conductivity was generally found to increase with pressure and fluid salinity. The conductivity increase observed upon variation of NaCl concentration from 0.1 to 1 M was smaller than from 0.01 to 0.1 M, which reflects the reduced degree of dissociation at high NaCl concentration. Measured conductivities can be reproduced (R ² = 0.96) by a numerical model with log \(\sigma\) = ?1.7060– 93.78/T + 0.8075 log c + 3.0781 log \(\rho\) + log \(\varLambda\) ₀(T, \(\rho\)), where \(\sigma\) is the conductivity in S m^?1, T is temperature in K, c is NaCl concentration in wt%, \(\rho\) is the density of pure water (in g/cm³) at given pressure and temperature, and \(\varLambda\) ₀ (T, \(\rho\)) is the molar conductivity of NaCl in water at infinite dilution (in S cm² mol^?1), \(\varLambda\) ₀ = 1573–1212 \(\rho\) + 537 062/T–208 122 721/T ². This model allows accurate predictions of the conductivity of saline fluids throughout most of the crust and upper mantle; it should not be used at temperatures below 100 °C. In general, the data show that already a very small fraction of NaCl-bearing aqueous fluid in the deep crust is sufficient to enhance bulk conductivities to values that would be expected for a high degree of partial melting. Accordingly, aqueous fluids may be distinguished from hydrous melts by comparing magnetotelluric and seismic data. H₂O–NaCl fluids may enhance electrical conductivities in the deep crust with little disturbance of v _p or v _p/v _s ratios. However, at the high temperatures in the mantle wedge above subduction zones, the conductivity of hydrous basaltic melts and saline aqueous fluids is rather similar, so that distinguishing these two phases from conductivity data alone is difficult. Observed conductivities in forearc regions, where temperatures are too low to allow melting, may be accounted for by not more than 1 wt% of an aqueous fluid with 5 wt% NaCl, if this fluid forms a continuous film or fills interconnected tubes.  相似文献   

沙土在孔隙水注入实验中渗透剪切破坏          下载免费PDF全文

Kazama M  Uzuoka R  Sento N  N Unno T 《地震工程学报》2005,27(3):212-219

前人曾指出液化后伴随着超孔隙水压重新分配的渗透会引起流体破坏的可能性。为了研究这一现象,利用实验室三轴试验将孔隙水注入土壤检测了土壤的渗透剪切破坏。该实验是在各项异性的固结作用后保持差应力,使用孔隙水控制装置在体积不变的应变控制条件下将孔隙水注入。实验中所用的材料是在1995年神户地震时被液化的常规洁净细砂和风化的花岗岩土壤。本文以实验结果为基础,讨论了由孔隙水注入引起的渗透剪切破坏判据和导致后液化行为的剪切应变发展特征。  相似文献   

High-resolution observations of the Orion bright bar     

Omodaka  Toshihiro  Hayashi  Masahiko  Suzuki  Saeko  Hasegawa  Tetsuo  Miyawaki  Ryosuke 《Astrophysics and Space Science》1986,118(1-2):401-404

High resolution strip maps of CS (J=1–0) and H51 line emission across the Orion bright bar are presented. They reveal the existence of a high density molecular layer (molecular sheet) plane parallel to the ionization front. This molecular sheet is redshifted relative to the ambient molecular cloud by about 2 km s^–1. The rapid decrease of the CS emission at about 50 arc sec from the bar suggests that a shock front exists here and the sheet is a post shock layer.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.This work was carried out under the common use observation program at the Nobeyama Radio Observatory (NRO). NRO, a branch of the Tokyo Astronomical Observatory, University of Tokyo, Japan, is a cosmic radio observing facility open to outside users.  相似文献