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1.
Toshiki Aikawa 《Astrophysics and Space Science》1986,125(2):325-330
The short-period limiting pulsation found by Fadeyev and Fokin (1985) in a short-period, Population II Cepheid model is examined by means of the Baker-von Sengbush-Stellingwerf (BSS) algorithm of limit cycles.It is shown that the model has a stable limit cycle of the fundamental mode and an unstable limit cycle of the first overtone mode. When the method is applied for pulsations spanning the time interval of twice the period of the fundamental mode, we find only the fundamental cycle repeated doubly or the first overtone limit cycle repeated three times, depending on initial conditions of the integration.We thus conclude that the period-doubling limiting pulsation found by Fadeyev and Fokin (1985) is a transient feature of the model. 相似文献
2.
Infrared (IR) and nearinfrared (NIR) absorption spectra of hydrous and F-rich topazes were measured to assign an OH bending
mode of topaz. Three absorption peaks at 1165, 3650, and 4803 cm−1 are assigned to OH related absorption peaks. Since a peak at 4803 cm−1 can be assigned to a combination mode of 1165 and 3650 cm−1, the 1165 cm−1 peak is harmonic with the 3650 cm−1 peak. Polarized IR absorption spectra of (100), (010), and (001) planes of the hydrous topaz were measured to examine IR
active orientation of the 1165 cm−1 OH related mode. Three pleochroic distributions of the absorption peak at 1165 cm−1 on (100), (010), and (001) planes indicate an active orientation of the 1165 cm−1 OH related mode. The IR active orientation of the 1165 cm−1 OH related mode in topaz is normal to the OH dipole. The orthogonality and harmonic combination mode indicate that the 1165 cm−1 peak is OH bending mode. The active orientation of OH bending mode is polarized in the plane normal to the OH dipole. The
polarization suggests that anisotropic thermal vibration of protons on the hydroxyl is maximum along the IR active orientation.
Received: August 16, 1996 / Revised, accepted: April 20, 1997 相似文献
3.
Tadashi Akamatsu Mineo Kumazawa Nobuyuki Aikawa Humihiko Takei 《Physics and Chemistry of Minerals》1993,19(7):431-444
The divalent cation distribution in olivine (Mg, Fe)2SiO4 under high pressure and temperature was studied to clarify the detailed state of olivine in the mantle. Single crystal samples were heated for a sufficient period of time for the cations to migrate and quenched fast enough to preserve the equilibrated state under high pressures, and the crystal structure was determined with X-ray method. The pressure effect on the distribution coefficient K D[= (Fe/Mg) M1/(Fe/Mg) M2] was determined for the first time; dK D/dP?0.02 GPa?1. A set of five thermodynamic parameters required to describe the regular solution model was determined from data concerning the pressure dependence and the known temperature and compositional effects. As a result we have shown how K D depends on pressure, temperature, and composition. The notable feature clarified is the very large contribution of nonideality in the olivine solid solution. The K D of olivine crystals in the mantle is predicted; K D increases to ～ 2.2 at the depth of 400 km, in contrast to 0.9 ～ 1.2 of natural samples available at the surface of the Earth. 相似文献
4.
In order to investigate the behaviour of proton in brucite under pressure, polarized IR absorption spectra and polarized absorbance
distributions of (001) and (110) oriented single crystal of brucite under high pressure were measured by Fourier transform
polarized infrared microspectroscopy with diamond anvil cell. A pressure-induced absorption peak at 3645 cm−1 observed under pressures over 2.9 GPa was confirmed to be due to a secondarily formed OH dipole. Polarized absorbance distribution
measured under pressure of (110) suggests that the secondary OH dipole is oriented 136.0° to c-axis under 5.3 GPa. Isotropic
absorbance distribution of (001) suggests that the secondary OH dipole is disorderly trifurcated. Abrupt onset of the secondary
peak and its reverse pleochroism suggest that the process of secondary OH dipole formation is due to proton transfer between
layers in brucite. The calculated orientation of the secondary OH dipole consistent with the O-H···O′ angle revealed by neutron
diffraction supports the existence of proton transfer along H···O′. The secondary OH dipole implies a new site of proton in
brucite under pressure.
Received: 6 March 1997 / Revised, accepted: 9 June 1997 相似文献
5.
A comprehensive study on the chemistry of deposition and the concentration of tropospheric ozone and particulate sulfate in the ocean atmosphere was carried out for the data sets in 1990’s. It is important to study the atmospheric situation over the past years as well as the latest, especially in the East Asian region where emission amount of anthropogenic air pollutants have increased year by year due to rapid economic growth. The survey was conducted for 5 years in East Asia and West Oceania (35°N–35°S, 100–135°E) in August and September in 1990’s. The purpose of the survey was to study and understand the chemistry of deposition and the concentration of tropospheric ozone and particulate sulfate in the ocean atmosphere comprehensively in one project. Rainfall over the ocean was insufficiently neutralized. Gas and aerosol over the ocean were mature, i.e., well-mixed, during the period of the transportation. The characteristic latitudinal dependence was observed in the tropospheric ozone concentration, namely, higher in the southern hemisphere and lower in the northern hemisphere (approximately 25 ppb in the 10–40°S region and 5–15 ppb in the 20–40°N region). On the other hand, high concentrations of tropospheric ozone of over 30 ppb were observed in the northern hemisphere, which was attributable to the long-range transportation. The TSP concentration was approximately under the level of 40 μg m?3 irrespectively of the latitude; in contrast, the nss-SO4 2- concentration showed a clear latitudinal dependence, i.e., higher in the northern hemisphere and lower in the southern hemisphere. The background levels of the nss-SO4 2- concentration were approximately 0.5 μg m?3 in the 10–40°S region and 2–3 μg m?3 and 4–5 μg m?3 in the 0–20°N and 20–40°N regions, respectively. 相似文献
6.
T. Aikawa 《Astrophysics and Space Science》1993,210(1-2):269-280
Phenomena of bifurcation in hydrodynamic stellar models of radial pulsation are reviewed. By changing control parameters of models, we can see qualitatively different pulsation behaviors in hydrodynamic models with transitions due to various types of bifurcation.In weakly dissipative models (classical Cepheids), the bifurcation is induced by modal resonances. Two types of the modal resonances found in models are discussed: The higherharmonic resonances of the second overtone mode in the fundamental mode pulsator and of the fourth overtone mode in the first overtone pulsator are relevant to observations. The subharmonic resonance between the fundamental and first overtone modes is confirmed in classical Cepheid models.In strongly dissipative models (less-massive supergiant stars), the bifurcation of nonlinear pulsation is induced by the hydrodynamics of ionization zones as well as modal resonances. The sequence of the bifurcation sometimes leads to chaotic behaviors in nonlinear pulsation. The transition routes from regular to the chaotic pulsations found in models are discussed with respect to the theory of chaos in simple dynamical systems: The cascade of period-doubling bifurcation is confirmed to cause chaotic pulsation in W Virginis models. For models of higher luminosity, the tangent bifurcation is found to lead intermittent chaos.Finally, hydrodynamic models for chaotic pulsation with small amplitudes observed in the post-AGB stars are briefly discussed. 相似文献
7.
Toshiki Aikawa 《Astrophysics and Space Science》1984,104(2):405-408
It is shown that the coincidence between the pulsation periods and the critical frequencies found by Fadeyev (1982) results from strong effects of non-adiabaticity on the linear pulsation periods in low surface gravity models. If we apply the boundary condition of running waves for super-critical pulsations, it is found that the linear growth-rates are considerably affected by the boundary condition. 相似文献
8.
We found a hydrodynamic pulsation model of yellow supergiants under subharmonic resonance. It is confirmed that the feature of pulsation by the resonance is long-lived in the model by performing the hydrodynamical simulation for a long time. 相似文献
9.
Masahide Aikawa Takatoshi Hiraki Yosuke Horie Ryouhei Nakatsubo Chisato Matsumura Hitoshi Mukai 《Journal of Atmospheric Chemistry》2017,74(4):505-518
The seasonal intensive sampling of gases and particulate matter in ambient air was conducted at the site established in urban area of Japan to study the seasonal difference of the temporal variation of gases and particulate matter concentrations in urban atmosphere as well as to illustrate the different transport regimes that impacts air pollutants. The sample was collected by the four-stage filter-pack method with 6-h interval for one week in four seasons (spring, summer, autumn and winter). The trans-boundary transport of air pollutants with high concentration was characteristically observed in the spring sampling. On the other hand, we could successfully detect the in-country transports of air pollutants in the summer sampling. Four-season’s intensive survey considered, we could show the characteristic transport of air pollutants to provide the episodic high concentration for ambient air in the urban area of Japan, and successfully illustrate the seasonal-dependent transport regimes to impact on air pollutants. 相似文献
10.
For the purpose of determining the orientation of the OH? dipole in an optically anisotropic crystal, distribution of polarized IR absorbance is formulated under Fourier transform microspectroscopy. The formulatd absorbance distribution suggests that the degree of pleochroism of absorbance depends on the angle between the orientation of the OH? dipole and the principal orientation of the optically anisotropic crystal. As its application, the general orientation of the OH? dipole in topaz is determined to be inclined 27.3° from the c-axis in (010). 相似文献