Records of environmental and ecological changes related to excavation in varve sediment from Lake Hiruga in central Japan     

Seto  Koji  Katsuki  Kota  Tsujimoto  Akira  Kitagawa  Junko  Yamada  Kazuyoshi  Suzuki  Yoshiaki 《Journal of Paleolimnology》2022,68(3):329-343

Journal of Paleolimnology - Sub-annual-scale environmental and ecosystem changes since the mid-18th century were reconstructed in a semi-closed lagoon, Lake Hiruga, located along the Sea of Japan...  相似文献   

Methods to correct the variable graduation error of the meridian circle     

M. Miyamoto  S. Suzuki 《Astrophysics and Space Science》1991,177(1-2):251-257

In the automated(computerized) meridian circle, the graduation error can be calibrated in a short time: a complete determination of the graduation error takes a few days, while a coarse measurement of the first ten dominant Fourier components of the graduation error takes only 15 min. Thus, we can monitor the annual and diurnal variations of the graduation. In our regular observations, the annual variation can be thus corrected for. This kind of correction seems to be necessary, judging from the observing accuracy of modern meridian observations. On the other hand, we could not detect a change of the graduation within one clear day as far as the dominant components of the diameter error are concerned. In our case we can therefore assume the graduation error to be constant within one day.  相似文献   

Transient crater growth in granular targets: An experimental study of low velocity impacts into glass sphere targets     

Satoru Yamamoto  Koji Wada  Takafumi Matsui 《Icarus》2006,183(1):215-224

We experimentally studied the formation and collapse processes of transient craters. Polycarbonate projectiles with mass of 0.49 g were impacted into the soda-lime glass sphere target (mean diameters of glass spheres are ∼36, 72, and 220 μm, respectively) using a single-stage light-gas gun. Impact velocity ranged from 11 to 329 m s⁻¹. We found that the transient crater collapses even at laboratory scales. The shape (diameter and depth) of the transient crater differs from that of the final crater. The depth-rim diameter ratios of the final and transient craters are 0.11-0.14 and 0.26-0.27, respectively. The rim diameter of both the transient and final crater depends on target material properties; however, the ratio of final to transient crater diameter does not. This suggests that target material properties affect the formation process of transient craters even in the gravity regime, and must be taken into account when scaling experimental results to planetary scales. By observing impacts into glass sphere targets, we show that although the early stage of the excavation flow does not depend on the target material properties, the radial expansion of the cavity after the end of vertical expansion does. This suggests that the effect of target material properties is specifically important in the later part of the crater excavation and collapse.  相似文献   

Physics in Next Geoneutrino Detectors     

Atsuto Suzuki 《Earth, Moon, and Planets》2006,99(1-4):359-368

The KamLAND liquid scintillator detector demonstrated the detection of antineutrinos produced by natural radioactivities in the Earth, so-called geoneutrinos. Although this first result of geoneutrinos is consistent with current geophysical models, more accurate measurements are essential to provide a new window for exploring the inside of the Earth. In this article I would like to discuss the future prospects of KamLAND geoneutrino detection, and the possibility of directional measurement of incoming geoneutrinos. It is interesting to consider the application of geoneutrino detectors to measurements of other neutrino signals. The possibility of detecting the solar 7Be, pep and CNO neutrinos is discussed. A new type detector concept is proposed not only to explore the precise measurement of reactor neutrino oscillations but also to enable us to realize the neutrino tomography inside the Earth.  相似文献   

VIDEO AND PHOTOGRAPHIC SPECTROSCOPY OF 1998 AND 2001 LEONID PERSISTENT TRAINS FROM 300 TO 930 nm     

Shinsuke Abe  Noboru Ebizuka  Hideyuki Murayama  Katsuhito Ohtsuka  Satoru Sugimoto  Masa-yuki Yamamoto  Hajime Yano  Jun-ichi Watanabe  Jiří Borovička 《Earth, Moon, and Planets》2004,95(1-4):265-277

Spectra of persistent meteor trains were observed at wavelength between 300 and 930 nm. Two obtained train spectra during the 1998 and 2001 Leonid meteor showers are reported here. During the 1998 Leonids, one train was detected by a photographic camera with a spectrograph covering 370–640 nm region. On the other hand, during the 2001 Leonids, video observations were carried out using image intensified cameras in ultraviolet (UV), visible and near infrared (near-IR) wavelengths. Temperatures in persistent trains have been measured by atmospheric O₂ A(0,1) band at the wavelength near 864.5 nm. From a video spectrum obtained just 7 s after parent fireball’s flare, a rotational temperature of 250 K at altitude of 88.0±0.5 km was estimated. We can say that the cooling time scale of train strongly depends on the initial mass of its fireball at least for Leonids. Based on cooling constant calculated from our results, we estimated a temperature of ∼ ∼130 K as a final exothermic temperature at early stage of persistent trains.  相似文献   

Evolution of disk galaxies regulated by supernova remnants     

Yutaka D. Tanaka  Satoru Ikeuchi  Asao Habe 《Astrophysics and Space Science》1986,119(1):207-210

Assuming that a disk galaxy is composed of an ambient pervasive gas, small clouds, molecular clouds and stars, its evolution is studied through examining the interchange processes among them. Main results obtained are: (1) The star formation rate is directed by the formation process of molecular clouds. (2) Depending upon the parameters there may be three or four types of evolution of disk galaxies: the no star formation case, the active in the past and inactive at present star formation case, the burst-like star formation case and the very active in star formation case.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan between 30 September–6 October, 1984.  相似文献   

Regional 3-D heterogeneities by waveform inversion – application to the Atlantic area     

Satoru Honda  Toshiro Tanimoto 《Geophysical Journal International》1987,91(3):737-753

The waveform inversion method described in Woodhouse & Dziewonski (1984) was modified to retrieve regional scale 3-D heterogeneities by using the minor arc part of seismograms. The lateral heterogeneities are expanded horizontally into blocks (10°× 10°) and radially into Legendre polynomials up to order 3 (0–670 km), and thus the results show much fine details of lateral variation than previous global scale studies. We assumed that the heterogeneities produce the perturbation of eigenfrequencies which are the minor arc average of local eigenfrequency shift. We applied the method to the upper mantle beneath the Atlantic Ocean and its environments. Care was taken about the weighting of the data set. We found that the fit of each seismogram became better when the weighting of each seismogram is proportional to the inverse of initial data residuals. Resolution is good in the triangular region surrounded by South America, Europe, and North America. Resolution is not good in the South Atlantic because of the poor path coverage. Depth resolution is not clear, because of the use of Legendre polynomials, though the results suggest a broad half-width of the order of 200 km or more. We found some similarities between previous global studies and our results. For example, low velocities beneath the East Pacific Rise, Chile Rise and Azores triple junction and a high velocity Canadian shield are obtained. However, there are also differences; the high-velocity zone beneath the Brazilian shield at shallow depth is not a prominent feature in this study. Instead, we found a somewhat unexpected feature near the Romanche and Vema fracture zones where shallow positive anomalies exist. Smoothed results calculated by the spherical harmonic expansion are also shown for the purpose of comparison with global studies.  相似文献   

Physical parameters identification for full-scale ten-story reinforced concrete building with degrading tri-linear model by modal iterative error correction method     

Takuya Uesaka  Kunihiko Nabeshima  Naohiro Nakamura  Takuya Suzuki 《地震工程与结构动力学》2022,51(1):153-168

To assess the post-earthquake seismic safety of buildings, it is crucial to predict seismic response, and it is necessary to set the appropriate physical parameters of the response analysis model. Numerous methods have been proposed to identify physical parameters. However, most of them are limited to linear systems, and previous researches on nonlinear systems have difficulties in practical applications. In this paper, a nonlinear response analysis model is identified for a full-scale ten-story reinforced concrete building with the degrading tri-linear stiffness model by the modal iterative error correction (MIEC) method, and the accuracy of this technique is discussed by comparing with the shaking table test.  相似文献   

Interaction of intergalactic-gas flow with a rigid-body,spheroidal galaxy     

Satoru Ikeuchi  Kohji Tomisaka 《Astrophysics and Space Science》1981,80(2):483-500

The interaction of intergalactic-gas flow, which is assumed to be an incompressible fluid, with a rigid-body, spheroidal galaxy is examined analytically. The gas-flow patterns, the distributions of pressure at the surface of galaxy and some other quantities are calculated for the cases with and without viscosity. By use of results, we discuss the formation of HI ridges, trailing clouds and gas streams accompanying with galaxies, and the bending (or warping) of intersteller gas observed in spiral galaxies are analyzed. Some discussion on the Magellanic Stream is given.  相似文献   

Relation between X-ray flux and radio flux from cosmic objects     

Ikuro Suzuki 《Astrophysics and Space Science》1983,97(1):145-150

The relationship between the X-ray flux and the radio flux from cosmic objects is investigated. We consider the emission from energetic electrons on the condition in which a plasma and a magnetic field exist. As energetic electrons under the circumstances emit both X-rays by the bremsstrahlung mechanism and radio waves by the gyrosynchrotron mechanism simultaneously, it is shown that the radio flux density is closely related to the X-ray flux density. Solving an integral equation describing the X-ray flux density at Earth, we obtain the energy spectrum of electrons in the emitting region. Inserting the result into equation of the radio flux density at Earth, we obtain the direct formula between the X-ray flux density and the radio flux density. The relation is independent of the distance between Earth and cosmic sources. Assuming a power-law X-ray spectrum, we evaluate the numerical relation between two flux densities.  相似文献