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51.
We have developed a wind-wave-surge coupled process-based numerical model for simulating storm surge, consisting of a meso-scale atmospheric model (MM5), a third-generation spectral wave model (WW3) and a coastal ocean model (POM). We introduced an additional sea surface shear stress by wave dissipation into the model to consider the process of energy transfer from winds to currents through whitecap breaking. We demonstrate the importance of this energy transfer path through a hindcast simulation of a cyclone surge in April, 1991 in the Bay of Bengal: it helps generate mean current and has wave effects on wind-induced current fields in extremely shallow water areas. 相似文献
52.
Takao Fukui 《Astrophysics and Space Science》1988,141(2):407-413
The geodesic equation in a viable 5D space-time-mass theory of gravity is calculated for the purpose of presenting quantities accessible to experiments and observations. Determining the values of the constants in the theory is left for future tests concerning the principle of equivalence. But qualitatively we can show that the five-velocity is a function of not only of time but also mass. And in general case a possible change of mass depends onm as well ast. 相似文献
53.
The Space Infrared telescope for Cosmology and Astrophysics (SPICA) is planned to be the next space astronomy mission observing
in the infrared. The mission is planned to be launched in 2017 and will feature a 3.5 m telescope cooled to <5 K through the
use of mechanical coolers. These coolers will also cool the focal plane instruments thus avoiding the use of consumables and
giving the mission a long lifetime. SPICA’s large, cold aperture will provide a two order of magnitude sensitivity advantage
over current far infrared facilities (>30 microns wavelength). We describe the scientific advances that will be made possible
by this large increase in sensitivity and give details of the mission, spacecraft and focal plane conceptual design.
相似文献
Bruce SwinyardEmail: |
54.
Chiaki Hikage Kazuya Koyama Takahiko Matsubara Tomo Takahashi Masahide Yamaguchi 《Monthly notices of the Royal Astronomical Society》2009,398(4):2188-2198
We study the effect of primordial isocurvature perturbations on non-Gaussian properties of cosmic microwave background (CMB) temperature anisotropies. We consider generic forms of the non-linearity of isocurvature perturbations which can be applied to a wide range of theoretical models. We derive analytical expressions for the bispectrum and the Minkowski Functionals for CMB temperature fluctuations to describe the non-Gaussianity from isocurvature perturbations. We find that the isocurvature non-Gaussianity in the quadratic isocurvature model, where the isocurvature perturbation S is written as a quadratic function of the Gaussian variable σ, S =σ2 −〈σ2 〉 , can give the same signal-to-noise ratio as f NL = 30 even if we impose the current observational limit on the fraction of isocurvature perturbations contained in the primordial power spectrum α. We give constraints on isocurvature non-Gaussianity from Minkowski Functionals using the Wilkinson Microwave Anisotropy Probe ( WMAP ) 5-year data. We do not find a significant signal of isocurvature non-Gaussianity. For the quadratic isocurvature model, we obtain a stringent upper limit on the isocurvature fraction α < 0.070 (95 per cent CL) for a scale-invariant spectrum which is comparable to the limit obtained from the power spectrum. 相似文献
55.
Amirhomayoun Saffarzadeh Takayuki Shimaoka Hirofumi Nakayama Takao Hanashima Kentaro Yamaguchi Kazutoshi Manabe 《Natural Hazards》2017,88(3):1273-1295
The potential impacts of tsunamis along the Catalan Coast (NW Mediterranean) are analysed using numerical modelling. The region is characterized by moderate to low seismic activity and by moderate- to low-magnitude earthquakes. However, the occurrence of historical strong earthquakes and the location of several active offshore faults in front of the coast suggest that the possibility of an earthquake-triggered tsunami is not negligible although of low probability. Up to five faults have been identified to generate tsunamis, being the highest associated possible seismic magnitudes of up to 7.6. Coastal flooding and port agitation are characterized using the Worst-case Credible Tsunami Scenario Analysis approach. The results show a multiple fault source contribution to tsunami hazard. The shelf dimensions and the existence of submerged canyons control the tsunami propagation. In wide shelves, waves travelling offshore may become trapped by refraction causing the wave energy to reach the coastline at some distance from the origin. The free surface water elevation increases at the head of the canyons due to the sharp depth gradients. The effects of potential tsunamis would be very harmful in low-lying coastal stretches, such as deltas, with a high population concentration, assets and infrastructures. The Ebro delta appears to be the most exposed coast, and about the 20% of the delta surface is prone to flooding due to its extremely low-lying nature. The activity at Barcelona port will be severely affected by inflow backflow current at the entrance of up to 2 m/s. 相似文献
56.
Jonny Rutqvist Ann Bäckström Masakazu Chijimatsu Xia-Ting Feng Peng-Zhi Pan John Hudson Lanru Jing Akira Kobayashi Tomofumi Koyama Hee-Suk Lee Xiao-Hua Huang Mikael Rinne Baotang Shen 《Environmental Geology》2009,57(6):1313-1324
This simulation study shows how widely different model approaches can be adapted to model the evolution of the excavation
disturbed zone (EDZ) around a heated nuclear waste emplacement drift in fractured rock. The study includes modeling of coupled
thermal-hydrological-mechanical (THM) processes, with simplified consideration of chemical coupling in terms of time-dependent
strength degradation or subcritical crack growth. The different model approaches applied in this study include boundary element,
finite element, finite difference, particle mechanics, and elasto-plastic cellular automata methods. The simulation results
indicate that thermally induced differential stresses near the top of the emplacement drift may cause progressive failure
and permeability changes during the first 100 years (i.e., after emplacement and drift closure). Moreover, the results indicate
that time-dependent mechanical changes may play only a small role during the first 100 years of increasing temperature and
thermal stress, whereas such time-dependency is insignificant after peak temperature, because of decreasing thermal stress. 相似文献
57.
We report on the diffuse X‐ray emission from the Galactic Centre (GCDX) observed with the X‐ray Imaging Spectrometer (XIS) on board the Suzaku satellite. The highly accurate energy calibration and extremely low background of the XIS provide many new facts on the GCDX. These are (1) the origin of the lines at 6.7 and 7.0 keV is collisional excitation in a hot plasma, (2) the discovery of new SNR and super‐bubble candidates, (3) most of the 6.4 keV line is X‐ray fluorescence, and (4) time variability of the 6.4 keV line is found from the Sgr B2 complex. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
58.
Takao Fukui 《Astrophysics and Space Science》1988,149(1):13-18
The bi-variational technique is used to calculated Chandrasekhar'sX- andY-functions and their first two moments for an isotropic homogeneous finite slab. Numerical results obtained are compared with published results. 相似文献
59.
Magnetic pulsation Pi2 and substorm onset 总被引:1,自引:0,他引:1
Coincidence between the onset of sudden brightening of the auroral arc in the auroral oval and the onset of Pi2 magnetic pulsation in low latitudes is examined based on the auroral data obtained at a chain of stations in Alaska and the Pi2 data obtained at the low-latitude station Onagawa. The result shows that the low-latitude Pi2 occurs almost simultaneously with the sudden brightening of the auroral arc, i.e. the onset of an auroral substorm (T = 0). It is concluded that the onset of substorms can be identified quite well with the onset of the low-latitude Pi2. 相似文献
60.
H emission objects were searched for, using the objective-prismSchmidt plates in a 36 deg2 sky area covering the Cepheus OB3 association.Hundred and eight emission stars have been found, 68 of which are newfindings to our knowledge. The properties of the IRAS point sourcesidentified with H emission stars indicate that most of theH emission stars are T Tauri stars or related objects. Hemission stars associated with IRAS sources and those unassociated havedifferent distributions, suggesting an age sequence among them.Altogether, they show a ring- or shell-like surface distribution, whichalmost coincides with that of heated dusts, and these distributionsappear to be encompassed by an HI shell. 相似文献