Induced fabric under cyclic and rotational loads in a strain space multiple mechanism model for granular materials     

Susumu Iai  Tetsuo Tobita  Osamu Ozutsumi 《国际地质力学数值与分析法杂志》2013,37(2):150-180

The strain space multiple mechanism model idealizes the behavior of granular materials on the basis of a multitude of virtual simple shear mechanisms oriented in arbitrary directions. Within this modeling framework, the virtual simple shear stress is defined as a quantity dependent on the contact distribution function as well as the normal and tangential components of interparticle contact forces, which evolve independently during the loading process. In other terms, the virtual simple shear stress is an intermediate quantity in the upscaling process from the microscopic level (characterized by contact distribution and interparticle contact forces) to the macroscopic stress. The stress space fabric produces macroscopic stress through the tensorial average. Thus, the stress space fabric characterizes the fundamental and higher modes of anisotropy induced in granular materials. Herein, the induced fabric is associated with monotonic and cyclic loadings, loading with the rotation of the principal stress, and general loading. Upon loading with the rotation of the principal stress axis, some of the virtual simple shear mechanisms undergo loading whereas others undergo unloading. This process of fabric evolution is the primary cause of noncoaxiality between the axes of principal stresses and strains. Although cyclic behavior and behavior under the rotation of the principal stress axis seem to originate from two distinct mechanisms, the strain space multiple mechanism model demonstrates that these behaviors are closely related through the hysteretic damping factor. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Air-sea gas transfer in a shallow,flowing and coastal environment estimated by dissolved inorganic carbon and dissolved oxygen analyses     

Osamu Abe  Atsushi Watanabe  V. V. S. S. Sarma  Yohei Matsui  Hiroya Yamano  Naohiro Yoshida  Toshiro Saino 《Journal of Oceanography》2010,66(3):363-372

We estimated gas exchange rates in Kabira Reef at Ishigaki Island, southwest Japan, using a mass balance calculation with dual “biological” tracers: dissolved inorganic carbon (DIC) and dissolved oxygen (DO). The nighttime results allowed us to obtain reasonable gas transfer velocity k _w values, all of which exceeded those obtained in wind-dominant studies. The difference is likely due to the contribution of turbulence generated by the interaction between the current and bottom topography. The k _w obtained during high tides is consistent with that reported by Raymond and Cole (2001), whereas k _w during low tides is significantly higher, which seems to be caused by enhanced friction with the bottom of the reef and/or bubble-induced gas transfer by wave breaking at the reef crest.  相似文献   

Excess heating of corona and chromosphere above magnetic regions by non-linear Alfvén waves     

Yutaka Uchida  Osamu Kaburaki 《Solar physics》1974,35(2):451-466

Excess heating of the active region solar atmosphere is interpreted by the decay of MHD slow-mode waves produced in the corona through the non-linear coupling of Alfvén waves supplied from subphotospheric layers. It is stressed that the Alfvén-mode waves may be very efficiently generated directly in the convection layer under the photosphere in magnetic regions, and that such magnetic regions, at the same time, provide the ‘transparent windows’ for Alfvén waves in regard to the Joule and frictional dissipations in the photospheric and subphotospheric layers. Though the Alfvén waves suffer considerable reflection in the chromosphere and in the transition layer, a certain fraction of this large flux is propagated out to the corona, and a large velocity amplitude exceeding the local Alfvén velocity is attained during the propagation along the magnetic tubes of force into a region of lower density and weaker magnetic field. The otherwise divergence-free velocity field in Alfvén waves gets involved in such a case with a compressional component (slow-mode waves) which again is of considerable velocity amplitude relative to the local acoustic velocity when estimated by using the formulation for non-linear coupling between MHD wave modes derived by Kaburaki and Uchida (1971). Therefore, the compressional waves thus produced through the non-linear coupling of Alvén waves will eventually be thermalized to provide a heat source. The introduction of this non-linear coupling process and the subsequent thermalization of thus produced slow-mode waves may provide means of converting the otherwise dissipation-free Alfvén mode energy into heat in the corona. The liberated heat will readily be redistributed by conduction along the magnetic lines of force, with higher density as a consequence of increased scale height, and thus the loop-like structure of the coronal condensations (or probably also the thread-like feature of the general corona) may be explained in a natural fashion.  相似文献   

An Ecosystem Services Approach to Sustainable Livelihoods in the Homegardens of Kandy,Sri Lanka     

Nicholas Landreth  Osamu Saito 《The Australian geographer》2014,45(3):355-373

ABSTRACT

The Kandyan homegardens, or forest gardens, of central Sri Lanka are diverse, smallholder agroforestry ecosystems that for 2000 years have reflected evolving environmental, economic, and social livelihood needs. An ecosystem services approach interrogated homegarden changes over the last 10 years in 31 Kandyan households. Livelihood strategies favouring homegardens were found to have broader benefits across household, national, and global scales than those favouring commercial simplification or those abandoning cultivation for alternative incomes. Livelihood benefits beyond income included resilience to economic and environmental shocks; food security; and higher stocks of biological and agricultural diversity. This revealed overlooked socio-ecological feedbacks between drivers that frustrated interventions to sustain homegarden livelihoods, including increased wild animal incursions thwarting household climate adaptation and disaster recovery; global organic and fair trade incentives reducing food security and livelihood resilience; and national seed and animal regulations counteracting homegarden sustainability programs. Despite these pressures, households maintained homegarden systems for their cultural, aesthetic and eating preferences. An ecosystem services approach can complement sustainable livelihood approaches by identifying overlooked environmental and cultural benefits; reveal livelihood feedbacks from drivers of ecosystem change; avoid unintended consequences from interventions; and capitalise on synergies between stakeholder priorities.  相似文献   

Teshima pyroclastics: Onset of characteristic Setouchi magmatism induced by slab melting at 14.8 Ma     

Reina Nakaoka  Soko Kado  Shuichi Hasegawa  Keiko Suzuki-Kamata  Osamu Ishizuka  Shun Sekimoto  Hiroshi Kawabata  Yoshiyuki Tatsumi 《Island Arc》2021,30(1):e12378

Ar-Ar ages, and petrographical and geochemical characteristics of pyroclastics and an overlying lava from Teshima Island, southwest Japan are presented. Although previous geological and age data suggested Teshima pyroclastics were products of magmatism > 3 my prior to lava flows of Setouchi volcanic rocks generated in association with southward migration of the southwest Japan arc sliver during opening of the Sea of Japan backarc basin at ~ 15 Ma, the present results led to the conclusion that a sequence of Setouchi volcanism, induced by slab melting and subsequent melt-mantle reactions, produced both pyroclastics and lava at 14.6–14.8 Ma. This age is oldest among those reported so far and may represent the timing of onset of characteristic Setouchi magmatism immediately posterior to and hence as a result of the mega-tectonic event including rotation of the southwest Japan arc sliver.  相似文献   

Electrodynamical synchronization of AM Herculis-type stars     

Osamu Kaburaki 《Astrophysics and Space Science》1986,119(1):85-88

A new mechanism is proposed for the explanation of synchronous rotations in AM Herculis-type binaries. In contrast to the resistive mechanism of Josset al. (1979), our model predicts that an asynchronous rotation, if it is present, damps exponentially and the damping time is inversely proportional to the electrical conductivity. It is shown by using the parameters which fit for AM Herculis that a typical damping time is very short compared with the lifetime of the system.Paper presented at the I.A.U. Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.  相似文献   

Remote sensing parameterization of the processes of energy and water cycle over desertification areas     

马耀明  TSUKAMOTO Osamu 《中国科学D辑(英文版)》2002,45(Z1)

In order to understand the processes of land surface-atmosphere interaction over de-sertification area, it is indispensable to utilize of satellite remote sensing. Two scenes of LandsatTM were used to produce a set of maps of surface reflectance, MSAVI, vegetation coverage, sur-face temperature, net radiation, soil heat flux, sensible heat flux and latent heat flux. Statisticalanalysis based on these maps revealed some quantitative significant land surface characteristics.Future developments of the method are also discussed.  相似文献   

海洋天然气水合物的地球物理研究(Ⅰ)：岩石物性   总被引：27，自引：5，他引：27  

宋海斌  郝天珧  松林修  吴能友 《地球物理学进展》2001,16(2):118-126

本文综述了含水合物沉积物的岩石物性模型，讨论水合物饱和度与岩石物性的关系，关于纵波速度与水合物饱和度的关系，有一些简单模型，如孔隙度降低模型，时间平均方程、时间平均－Wood加权方程，也有复杂模型，如根据弹性模量计算的模型、根据等效介质中地震波传播理论的模型，本文还介绍了含水合物沉积物的电阻率、电导率模型与含注重气沉积物的岩石物性。  相似文献   

Further Occurrence of Brown Ores in Kuroko-type Deposits in Japan     

Akira IMAI  Osamu ISHIZUKA  †  Ryoichi YAMADA  Hiroshi MIYAMOTO 《Resource Geology》2001,51(3):263-268

Abstract: The occurrence of so-called brown ore from the Kuroko-type deposits in Japan was examined. Brown ore specimens from the Kannondo, Inarizawa, Matsumine, Fukazawa, Uchinotai, Kosaka (orebody unknown) and Nurukawa deposits have been found in the ore collection stored by Dowa Mining Co. Ltd. and the subsidiary companies. In addition, occurrences from the Fukazawa, Matsumine, Ezuri, Shakanai, and Ginzan deposits were previously reported. The brown ore is characterized by its color and by its higher Ag concentration (up to around 2,400 g/t) than ordinary black ores. This type of ore occurs commonly in the Kuroko-type deposits in Japan, whereas its extent is limited. The brown ore is a type of Au-rich massive sulfide ore formed in submarine hydrothermal system.  相似文献   

Possible manifestations of slab window magmatisms in Cretaceous southwest Japan   总被引：3，自引：0，他引：3  

Osamu Kinoshita   《Tectonophysics》2002,344(1-2)

The slab window system related to ridge subduction is studied to explain the conspicuous activity and the along-arc migration of the magmatisms in the eastern margin of Eurasian continent in the late Mesozoic. The trend of the granite ages is scrutinized with systems approach and analyzed by the statistical method in Cretaceous southwest Japan, a reference field of the Eurasian eastern margin. The magmatic distribution of simultaneous activity was determined to be the V-shape of the slab window, excluding dating errors from the located age data. The slab window magmatism has the most dominant zone of the acidic rocks at or near the centerline of the window (the spreading center of two plates), and also has the subdominant zone of the acidic to intermediate rocks on either side of the window.As the slab window opens due to the plate motions, the upwelling current is adiabatically induced in the asthenosphere to fill the window gap. The partial melt is generated in the upwelling flux and transports heat to the lower crust to make greater granitic magma chambers by heat conduction to, and assimilation with, the crustal matter. The younger and hotter slabs outside the window also play a role in partial slab melting and/or dehydration to the asthenosphere and generate the subdominant granodioritic and adakitic and/or high-magnesian andesitic magmatisms as the pre- and post-activities of the main granite genesis.The slab window formed by the subducted ridge between the Kula and Pacific plates was the strong heat source of the active magmatisms and migrated at the rate of 2.8 cm/year from southwest to northeast about 8000 km along the continental margin. The growth of the continent associated with the active acidic to intermediate magmatisms including the adakitic and/or high-magnesian andesitic activities is modeled by the slab window system.  相似文献