摘要 :
Analysis of large deformation of geomaterials subjected to time-varying load poses a very difficult problem for the geotechnical profession. Conventional finite element schemes using the updated Lagrangian formulation may suffer f...
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Analysis of large deformation of geomaterials subjected to time-varying load poses a very difficult problem for the geotechnical profession. Conventional finite element schemes using the updated Lagrangian formulation may suffer from serious numerical difficulties when the deformation of geomaterials is significantly large such that the discretized elements are severely distorted. In this paper, an operator-split arbitrary Lagrangian-Eulerian (ALE) finite element model is proposed for large deformation analysis of a soil mass subjected to either static or dynamic loading, where the soil is modelled as a saturated porous material with solid-fluid coupling and strong material non-linearity. Each time step of the operator-split ALE algorithm consists of a Lagrangian step and an Eulerian step. In the Lagrangian step, the equilibrium equation and continuity equation of the saturated soil are solved by the updated Lagrangian method. In the Eulerian step, mesh smoothing is performed for the deformed body and the state variables obtained in the updated Lagrangian step are then transferred to the new mesh system. The accuracy and efficiency of the proposed ALE method are verified by comparison of its results with the results produced by an analytical solution for one-dimensional finite elastic consolidation of a soil column and with the results from the small strain finite element analysis and the updated Lagrangian analysis. Its performance is further illustrated by simulation of a complex problem involving the transient response of an embankment subjected to earthquake loading.
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The three dimensional dynamics of a spheromak--like compact toroid (SCT) plasmoid, which is injected into a magnetized target plasma region, is investigated by using MHD numer- ical simulations. It is found that the process of SCT...
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The three dimensional dynamics of a spheromak--like compact toroid (SCT) plasmoid, which is injected into a magnetized target plasma region, is investigated by using MHD numer- ical simulations. It is found that the process of SCT penetration into this region is much more complicated than that which has been analysed so far by using a conducting sphere (CS) model. The injected SCT suffers from a tilting instability, which grows with a similar timescale to that of the SCT penetration. The instability is accompanied by magnetic reconnection between the SCT magnetic field and the target magnetic field, which disrupts the magnetic configuration of the SCT. Magnetic reconnection plays a role in supplying the high density plasma, initially con- fined in the SCT magnetic field, to the target region. The penetration depth of the SCT high den- sity plasma is also examined. It is shown to be shorter than that estimated from the CS model. The SCT high density plasma is decelerated mainly by the Lorentz force of the target magnetic field, which includes not only the magnetic pressure force but also the magnetic tension force. Fur- thermore, by comparing the SCT plasmoid injection with the bare plasmoid injection, magnetic reconnection is considered to relax the magnetic tension force, i.e. the deceleration of the SCT plasmoid.
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High-resolution angle-resolved photoemission spectroscopy (ARPES) has been performed on quasi-one-dimensional (1D) compounds Nb_3X_4 (X = S, Se, Te). We have experimentally determined the band structure of these compounds and comp...
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High-resolution angle-resolved photoemission spectroscopy (ARPES) has been performed on quasi-one-dimensional (1D) compounds Nb_3X_4 (X = S, Se, Te). We have experimentally determined the band structure of these compounds and compared with several different band calculations. We found a fairly straight 1D Fermi surface in Nb_3Te_4 (charge density wave transition temperature T_(CDW) = 110 K, superconducting transition temperature T_c = 1.9 K), while the Fermi surface of Nb_3Se_4 (T_c = 2.4 K) and Nb_3S_4 (T_c = 3.8 K) shows a remarkable wiggling, indicative of the more two-dimensional-like (three-dimensional-like) character. We also found a sharp quasiparticle peak near the Fermi level (E_F) at low temperatures for Nb_3S_4 and Nb_3Se_4, while the spectral weight near E_F of Nb_3Te_4 is considerably suppressed. These experimental results indicate that the anisotropy of the electronic structure remarkably changes with varying the chalcogen atom in the compounds.
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摘要 :
High-resolution angle-resolved photoemission spectroscopy (ARPES) has been performed on quasi-one-dimensional (1D) compounds Nb_3X_4 (X=S,Se,Te). We have experimentally determined the band structure of these compounds and compared...
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High-resolution angle-resolved photoemission spectroscopy (ARPES) has been performed on quasi-one-dimensional (1D) compounds Nb_3X_4 (X=S,Se,Te). We have experimentally determined the band structure of these compounds and compared with several different band calculations. We found a fairly straight 1D Fermi surface in Nb_3Te_4 (charge density wave transition temperature T_(CDW)= 110 K, superconducting transition temperature T_c= 1.9 K), while the Fermi surface of Nb_3Se_4 (T_c=2A K) and Nb_3S_4 (T_c=3.8 K) shows a remarkable wiggling, indicative of the more two-dimensional-like (three-dimensional-like) character. We also found a sharp quasiparticle peak near the Fermi level (E_F) at low temperatures for Nb_3S_4 and Nb_3Se_4, while the spectral weight near E_F of Nb_3Te_4 is considerably suppressed. These experimental results indicate that the anisotropy of the electronic structure remarkably changes with varying the chalcogen atom in the compounds.
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Oxygen adsorption on a C-terminated α-Mo_2C(0001) surface has been investigated with Auger electron spectroscopy, low-energy electron diffraction, and angle-resolved photoemission spectroscopy utilizing synchrotron radiation. It ...
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Oxygen adsorption on a C-terminated α-Mo_2C(0001) surface has been investigated with Auger electron spectroscopy, low-energy electron diffraction, and angle-resolved photoemission spectroscopy utilizing synchrotron radiation. It is found that the oxygen atoms adsorb on the Mo atoms in the second layer forming a (1 × 1) orthorhombic periodicity. The oxygen adsorption induces a peculiar state around the Fermi level, which is observed at 0.4 eV in the normal-emission spectra. ARPES measurements show that the state is a partially occupied metallic state. The photoionization cross section of the state shows a maximum at the photon energy of 56 eV, which is assigned as originating from the resonance of the Mo 4d photoemission involving Mo 4p→ 4d photoexcitation.
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The intensity of scintillation light emission from liquid xenon at room temperature was measured. The scintillation light yield at 1 ℃ was measured to be 0.64 ± 0.02 (stat.) ±0.06 (sys.) of that at -100℃ Using the reported lig...
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The intensity of scintillation light emission from liquid xenon at room temperature was measured. The scintillation light yield at 1 ℃ was measured to be 0.64 ± 0.02 (stat.) ±0.06 (sys.) of that at -100℃ Using the reported light yield at -100℃(46 photons/keV), the measured light yield at 1 ℃ corresponds to 29 photons/keV. This result shows that liquid xenon scintillator provides high light yield even at room temperature.
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The remediation of heavy metal contaminated soil using plants is a technology worth developing. However, the overall effect of phytoremediation in high-density Pb polluted sites remains unknown. Especially, little information is a...
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The remediation of heavy metal contaminated soil using plants is a technology worth developing. However, the overall effect of phytoremediation in high-density Pb polluted sites remains unknown. Especially, little information is available about the effects of using plants to control lead polluted leachate. Thus, we investigated the control of leachate in a box-scale phytoremediation test using common buckwheat, a Pb hyperaccumulator, grown on Pb contaminated soil. In the presence of buckwheat, the change in volumetric water content was smaller than that of the control with rainfall. The total amount of Pb in the leachate strongly correlated with the amount of leachate and the decrease in the density of Pb in the leachate. During the cultivation period, the total amount of Pb leached in the control was 1.28mg per container, while in the presence of buckwheat the total amount of Pb was approximately 22.7% of the control. Moreover, with buckwheat cultivation, Pb polluted leachate resulting from rainwater was prevented. The results suggested that buckwheat was a Pb hyperaccumulator and also had a high ability for phytostabilization. Control of Pb polluted leachate using buckwheat was shown to be a phytoremediation technology applicable to heavily Pb contaminated sites.
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Ergosterol (ERG) is a sterol produced by most fungi, but not by most plants. Thus, measurement of ERG in cereals makes it possible to determine the presence of fungi in cereals that can cause quality problems, such as mycotoxin co...
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Ergosterol (ERG) is a sterol produced by most fungi, but not by most plants. Thus, measurement of ERG in cereals makes it possible to determine the presence of fungi in cereals that can cause quality problems, such as mycotoxin contamination. This study developed and performed a single-laboratory validation for a method to test for ERG in various cereals. ERG was extracted by refluxing samples for 1 h with methanol-sodium hydroxide. ERG was extracted from the extract with hexane and then purified using a silica gel cartridge column. ERG was then separated and detected by reverse-phase high-performance liquid chromatography (HPLC). 'Within-day' recoveries of ERG at low levels were 92-99% with relative standard deviations (RSDs) of 3.2-6.5%. 'Between-day' recoveries of ERG at low levels were 97% and RSDs were 4.2-10.2%, respectively. Average recoveries of ERG over the range from 1.0 to l00.0mg kg~(-1) were 81-105% and RSDs were 3.9-16.3%.
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We investigated the spin-splitting in an almost strain-free In_(0.89)Ga_(0.11)Sb/In_(0.88)Al_(0.12)Sb two-dimensional electron gas (2DEG) by magnetoresistance measurements at 1.5 K. A large effective gyromagnetic factor (g factor)...
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We investigated the spin-splitting in an almost strain-free In_(0.89)Ga_(0.11)Sb/In_(0.88)Al_(0.12)Sb two-dimensional electron gas (2DEG) by magnetoresistance measurements at 1.5 K. A large effective gyromagnetic factor (g factor) |g~*|=33-34 was obtained by means of the coincidence method, which assumes an effective mass m~*=0.021m_0 at the Fermi energy. In spite of the large g factor and the high mobility (μ=9.8 × 10~4 cm~2/V s), a vanishing spin-splitting was also found around B~0.8 T by analyzing the second derivative of the magnetoresistance. This effect originates from the interplay between the Rashba and Dresselhaus spin-orbit interactions, and we theoretically confirmed the fact that the Dresselhaus spin-splitting energy △E_(0D)=3.5 meV was more than twice as large as the Rashba spin-splitting energy △E(0R)= 1.5 meV. Moreover, we demonstrated that the theoretical curves of the normalized spin splitting, including the g factor and the spin-orbit interactions, were well fitted to the experimental points with the Dresselhaus spin-orbit interaction. Therefore, we concluded that the Dresselhaus spin-orbit interaction is dominant in our 2DEG in spite of its narrow band gap.
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A survey was undertaken of aflatoxin B_1 (AFB_1), B_2 (AFB_2), G_1 (AFG_1), G_2 (AFG_2), ochratoxin A (OTA), and fumonisin B_1 (FB_1), B_2 (FB_2) and B_3 (FB_3) contamination of various retail foods in Japan during 2004-05. The my...
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A survey was undertaken of aflatoxin B_1 (AFB_1), B_2 (AFB_2), G_1 (AFG_1), G_2 (AFG_2), ochratoxin A (OTA), and fumonisin B_1 (FB_1), B_2 (FB_2) and B_3 (FB_3) contamination of various retail foods in Japan during 2004-05. The mycotoxins were analysed by high-performance liquid chromatography (HPLC), liquid chromatography/mass spectrometry (LC/MS) or high-performance thin-layer chromatography (HPTLC). Aflatoxins (AFs) were detected in ten of 21 peanut butter and in 22 of 44 bitter chocolate samples; the highest level of AFB_1, 2.59 μg kg~(-1), was found in peanut butter. Aflatoxin contamination was not observed in corn products (n = 55), corn (n=110), peanuts (n=120), buckwheat flour (n = 23), dried buckwheat noodles (n = 59), rice (n = 83) or sesame oil (n = 20). OTA was detected in 120 out of 192 samples of oatmeal, wheat flour, rye, buckwheat flour, raw coffee, roasted coffee, raisin, beer, wine and bitter chocolate, but not in rice or corn products. OTA levels in the positive samples were below 13 μg kg~(-1). AFs and OTA intakes through the consumption of foods containing cacao were estimated using the data for mycotoxin contamination in bitter chocolate and those for the consumption of foods containing cacao in Japan.
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