Heating and reconnection of the emerging magnetic flux-tubes and the role of the interchange instability     

Yutaka Uchida  Takashi Sakurai 《Solar physics》1977,51(2):413-429

We propose in the present paper that the basic behaviors of newly-emerged magnetic regions (NEMR) as seen in EUV and soft X-rays from space are interpreted by the interchange instability of the magnetic field of NEMR in the global situation surrounding it.It is shown that the situation with the NEMR is unstable against the interchange instability, and a continual relaxation to the lower energy state, or a continual invasion of the magnetic flux of the NEMR to the ambient region in the form of fine bundles or thin sheets, will take place in a short time scale of ₁ L/V _A following the change in the boundary condition at the photosphere. The second and the final relaxation is shown to be the enhanced Joule dissipation in a time scale of hours to several days occurring in the thin current sheets on the interface of this intermingled structure which is distributed in a large volume. This hypothesis may provide an explanation for the heating of NEMR to an X-ray emitting temperature, which is otherwise rather difficult to explain. The observed fast reconnection without appreciable flares (except for some smaller brightenings) is another aspect which can be explained in the present hypothesis. Namely, since the situation with the NEMR is unstable for the interchange from the beginning, the stressed configuration is relaxed before storing appreciable energy in the form of magnetic stress and therefore without a drastic release of a large amount of stored stress energy in the form of a flare.  相似文献   

Distribution of ductile deformation around the Main Central Thrust zone at the frontal part of nappe in southeastern Nepal Himalaya     

Katsushi Sato  Harutaka Sakai  Tetsuo Kawakami 《Island Arc》2020,29(1)

A geological survey and morphological analysis of quartz grains were performed to investigate the distribution of ductile deformation caused by the Himalayan Main Central Thrust (MCT) around Dhankuta, southeastern Nepal. The MCT was mapped as the lithological boundary between the gneiss of the Higher Himalayan Crystalline (HHC) as the hanging wall and the inverted metamorphic sequence of the Lesser Himalayan Sediments (LHS) as the footwall. The MCT was found to truncate various stratigraphic levels of LHS and cuts a map‐scale gentle fold developed in the LHS. Ductile deformation was quantified by fractal dimension between size and perimeter of dynamically recrystallized quartz grains in bedded metaquartzite intercalated in both HHC and LHS. Serrate and polygonal shapes of quartz indicate large and small strain rates, respectively, when the temperature during ductile deformation was assumed to be uniform. A peak of strain rate was found at the lithological boundary with the peak width of ca. 500 m. Such a thin shear zone is favorable for producing frictional heat to promote the inverted metamorphism in LHS.  相似文献   

Sonophotocatalysis of endocrine-disrupting chemicals     

Tokumoto T  Ishikawa K  Furusawa T  Ii S  Hachisuka K  Tokumoto M  Tsai HJ  Uchida S  Maezawa A 《Marine environmental research》2008,66(3):372-377

Sonolysis and photolysis often exhibit synergistic effects in the degradation of organic molecules. An assay of fish oocyte maturation provides an appropriate experimental system to investigate the hormonal activities of chemical agents. Oocyte maturation in fish is triggered by maturation-inducing hormone (MIH), which acts on receptors on the oocyte surface. A synthetic estrogen, diethylstilbestrol (DES), possesses inducing activity of fish oocyte maturation, and a widely used biocide, pentachlorophenol (PCP), exhibits a potent inhibitory effect on fish oocyte maturation. In this study, the effects of the combined treatment by sonolysis with photolysis (sonophotocatalysis) to diminish the hormonal activity of DES and the maturation preventing activity of PCP was examined. By sonophotocatalysis, hormonal activity of DES was completely lost within 30min and the inhibiting activity of PCP was lost within 120min. These results demonstrated that sonophotocatalysis is effective for diminishing the endocrine-disrupting activity of chemical agents.  相似文献   

Tidal Correction of Altimetric Data in the Japan Sea   总被引：2，自引：0，他引：2  

Akihiko Morimoto  Tetsuo Yanagi  Akio Kaneko 《Journal of Oceanography》2000,56(1):31-41

Satellite altimetric data have been very useful in the study of variation in the eddy field of the ocean. In order to investigate the variation in the eddy field, we have to remove tidal signals from altimetric data. However, global tidal models do not have sufficient accuracy in marginal seas such as the Japan Sea. In this study, we carried out harmonic analysis of temporal fluctuations of sea surface height data in the Japan Sea measured by TOPEX/POSEIDON. We could eliminate the tidal signals from altimetric data of TOPEX/POSEIDON and also from ERS-2 altimetric data with use of the harmonic constants derived from TOPEX/POSEIDON and tide gauge data along the coast. We draw co-tidal and co-range charts in the Japan Sea using the result of the harmonic analysis of TOPEX/POSEIDON altimetric data and tide gauge data along the coast. The results obtained turn out to be very useful for the tidal correction of altimetric data from satellite in the Japan Sea.  相似文献   

Clockwise phase propagation of semi-diurnal tides in the Gulf of Thailand   总被引：2，自引：0，他引：2  

Tetsuo Yanagi  Toshiyuki Takao 《Journal of Oceanography》1998,54(2):143-150

The phase of semi-diurnal tides (M₂ and S₂) propagates clockwise in the central part of the Gulf of Thailand, although that of the diurnal tides (K₁, O₁ and P₁) is counterclock-wise. The mechanism of clockwise phase propagation of semi-diurnal tides at the Gulf of Thailand in the northern hemisphere is examined using a simple numerical model. The natural oscillation period of the whole Gulf of Thailand is near the semi-diurnal period and the direction of its phase propagation is clockwise, mainly due to the propagation direction of the large amplitude part of the incoming semi-diurnal tidal wave from the South China Sea. A simplified basin model with bottom slope and Coriolis force well reproduces the co-tidal and co-range charts of M₂ tide in the Gulf of Thailand.  相似文献   

In memoriam     

Zenzaburo Suemoto  E. Hiei  Y. Uchida 《Solar physics》1993,146(2):203-205

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Evaluation of the non-hydrostatic stress produced in a multi-anvil high pressure apparatus     

Jun-ichi Ando  Tetsuo Irifune  Toru Takeshita  Kiyoshi Fujino 《Physics and Chemistry of Minerals》1997,24(2):139-148

Olivine single crystals have been deformed under high confining pressure (P=5?GPa) and temperature (T=1400?°C) conditions in a multi-anvil high pressure apparatus. NaCl, diamond and NaCl+diamond (2:1 by volume) powders were encapsulated along with the olivine single crystals in order to produce a range of stress states. The change of the non-hydrostatic stress transmitted to the olivine samples, enclosed within these three different media, during heating has been evaluated by observation of dislocation microstructure and density. A higher differential stress can be generated with diamond powder (0.1?GPa) than with NaCl powder (0.02?GPa). Although an intermediate differential stress between 0.1?GPa and 0.02?GPa had been expected to be generated using NaCl+diamond powder, the generation of non-hydrostatic stress in the olivine sample was unsuccessful. This may be caused by the fact that compaction (or sintering) proceeded in the capsule throughout the experiments. The most important finding of these experiments is that a constant non-hydrostatic stress can be applied to a sample under very high pressure and temperature conditions within the multi-anvil high pressure apparatus for the duration of the experiment. This approach is therefore suitable for investigating the steady-state rheological properties of mantle minerals at near-mantle conditions.  相似文献   

Infrared detector for mid-infrared astronomy     

Tetsuo Nishimura 《Astrophysics and Space Science》1989,160(1-2):325-332

Recent developments of infrared detectors and arrays for mid-infrared astronomical observations are discussed with an emphasis on technical issues in designing and fabricating photometers and cameras. The discussion includes a small-scale silicon bolometer array being tested at the Steward Observatory.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.  相似文献   

Magnetic field and current sheets in the corona above active regions     

Takashi Sakurai  Yutaka Uchida 《Solar physics》1977,52(2):397-416

A new method for the calculation of coronal magnetic field is proposed and it is shown to reproduce the EUV features in the corona as observed by Skylab experiments satisfactorily well. One of the remarkable points is that it reproduces the loopy threads in the active region corona and also the large scale field lines connecting active regions. The existence of coronal current is expected wherever the present coronal-current-free model fails to represent the feature. A method of calculating the coronal sheet-current is also developed with the purpose of knowing the shape of the current sheet and the amount of magnetic stress energy stored due the the presence of it by comparing the calculated field configuration with the observed local distortion of the EUV threads. This may be used in pinning down the possible site of the flare and in discussing the flare occurrence in terms of the energy stored there.During the preparation of this work, Poletto et al. (1975) calculated the magnetic field shape in Schmidt's method to compare with the soft X-ray feature obtained by Skylab.  相似文献   

A Study on Residual Flow in the Gulf of Tongking   总被引：2，自引：0，他引：2  

Dinh-Van Manh  Tetsuo Yanagi 《Journal of Oceanography》2000,56(1):59-68

On the basis of observations of water temperature, salinity and wind during winter (December to following February) and summer (June to August) in the Gulf of Tongking, a robust diagnostic three-dimensional model has established that reveals the seasonal variation in residual flow, including wind-driven current, density-driven current and tide-induced residual current. It is shown that in the Gulf of Tongking the wind-driven current plays the most important role in the seasonal variation of residual flow field. Due to strong NE monsoon (9 m/s) during winter the residual flow (reaches 30 cm/s) is stronger than that in summer. At the surface the residual flow direction during winter is basically westward or southwestward, while during summer it is almost reversed.  相似文献