Twelve centuries of blooming dates of the cherry blossoms at the city of Kyoto and its own vicinity     

Dr. H. Arakawa 《Pure and Applied Geophysics》1955,30(1):147-150

Summary Blooming dates of the cherry blossoms at the city of Kyoto (old capital of Japan) and its own vicinity are given in chronological order extending over twelve centuries. Examination of this documentary evidence in Japan shows a long period from 11th century until 14th century colder than the average, while the years since have been characterized by earlier blooming even though there is a definite sequence of fluctuation between late and early.  相似文献   

CARTOGRAPHIE DES “PSEUDO-RESISTIVITES APPARENTES’ PAR PROFILAGE TELLURIQUE-TELLURIQUE ASSOCIE A LA MAGNETO-TELLURIQUE *     

PHAM VAN NGOC  D. BOYER  ET M. CHOUTEAU 《Geophysical Prospecting》1978,26(1):218-246

The magneto-telluric and telluric-telluric profiling techniques are presented, and then a new method which combines these two techniques for mapping a parameter defined as the “apparent pseudo-resistivity”. The results obtained for the uranium structures in the Cluff Lake district (Saskatchewan Canada) indicate the use of these different techniques in the detection of zones of conduction for surface zones and for deeper zones, and demonstrate the advantages of these methods over the usual electrical methods in problems of structural research.  相似文献   

The role of sticky interstellar organic material in the formation of asteroids     

T. Kudo  A. Kouchi  M. Arakawa  H. Nakano 《Meteoritics & planetary science》2002,37(12):1975-1983

Abstract— Collision experiments and measurements of viscoelastic properties were performed involving an interstellar organic material analogue to investigate the growth of organic grains in the protosolar nebula. The organic material was found to be stickiest at a radius of between 2.3 and 3.0 AU, with a maximum sticking velocity of 5 m s^?1 for millimeter‐size organic grains. This stickiness is considered to have resulted in the very rapid coagulation of organic grain aggregates and subsequent formation of planetesimals in the early stage of the turbulent accretion disk. The planetesimals formed in this region appear to be represent achondrite parent bodies. In contrast, the formation of planetesimals at <2.1 and >3.0 AU begins with the establishment of a passive disk because silicate and ice grains are not as sticky as organic grains.  相似文献   

ESSAI DE FILTRAGE NON-LINEAIRE APPLIQUE AUX PROFILS AEROMAGNETIQUES*     

HENRI NAUDY ET HENRI DREYER 《Geophysical Prospecting》1968,16(2):171-178

Digital aeromagnetic profiles recorded with a high accuracy can be filtered with an electronic computer. Linear filtering is not very efficient, because the frequency spectrum of a given anomaly is very wide. But other methods are possible which, through a step by step analysis of the profile, leave some categories of anomalies unaltered while they remove the others completely. Our method uses as a criterium the width of the anomalies; it distinguishes and processes differently “bell-shaped” and “multi-legged” anomalies. Some examples of the use of the method are shown.  相似文献   

Spin rates of fast-rotating asteroids and fragments in impact disruption     

Toshihiko Kadono  Masahiko Arakawa  Takashi Ito  Keiji Ohtsuki 《Icarus》2009,200(2):694-697

We present a new experimental result of fragment spin-rate in impact disruption, using a thin glass plate. A cylindrical projectile impacts on a side (edge) of the plate. Dispersed fragments are observed using a high-speed camera and the spin rates of fragments are measured. We find that the measured fragment spin-rate decreases with increasing size. Assuming that the rotational energy of fragments is supplied from the residual stress, the spin rate ω decreases with increasing fragment size r as ω∼r−1, which explains the above experimental results. This size-dependence is similar to that of the observed spin rates of small fast-rotating asteroids. Our results suggest that spin rates of fragments of small asteroids immediately after disruption may have a similar size-dependence, and can provide constraints on the subsequent spin-state evolution of small asteroids due to thermal torques.  相似文献   

Low-velocity collisions between centimeter-sized snowballs: Porosity dependence of coefficient of restitution for ice aggregates analogues in the Solar System     

Yuri Shimaki  Masahiko Arakawa 《Icarus》2012,221(1):310-319

Understanding the collisional behavior of ice dust aggregates at low velocity is a key to determining the formation process of small icy bodies such as icy planetesimals, comets and icy satellites, and this collisional behavior is also closely related to the energy dissipation mechanism in Saturn’s rings. We performed head-on collision experiments in air by means of free-falling centimeter-sized sintered snowballs with porosities from 44% to 80% at impact velocities from 0.44 m s^?1 to 4.12 m s^?1 at ?10 °C. In cases of porosity larger than 70%, impact sticking was the dominant collision outcome, while bouncing was dominant at lower porosity. Coefficients of restitution of snow in this velocity range were found to depend strongly on the porosity rather than the impact velocity and to decrease with the increase of the porosity. We successfully measured the compaction volume of snowballs after the impact, and it enabled us to estimate the dynamic compressive strength of snow with the assumption of the energy conservation between kinetic energy and work for deformation, which was found to be consistent with the upper limit of static compressive strength. The velocity dependence of coefficients of restitution of snow was analyzed using a Johnson’s model, and a diagram for collision outcomes among equal-sized sintered snowballs was successfully drawn as a function of porosity and impact velocity.  相似文献   

The criterion of dynamic stability of zonal motion including the vertical shear     

Dr. H. Arakawa 《Pure and Applied Geophysics》1951,20(1):56-61

Summary Many writers treated on the problem of dynamic instability of westerly flow due to the excessive horizontal shear, and the present author discusses the corresponding dynamic instability due to the vertical shear. The critical vertical shear in indifferent stratification is given by the condition — the meridional component of absolute vorticity vanishes, — and is an approximate negative valueof 10^–4 sec ^–1 in middle latitude. However the critical vertical shear in normal stable stratification is a fairly large negative value of 2 sec^–1. It might be emphasized that the problem of this study differs fromRichardson's criterion of turbulence, for the present author discusses the condition under which the zonal flow is dynamically stable, whileRichardson expressed the condition under which the turbulence will decrease.  相似文献   

Geoarchaeological investigation of lithic resources in the central Mesa Verde region,Colorado, USA     

Fumiyasu Arakawa  Kimberlee Miskell‐Gerhardt 《Geoarchaeology》2009,24(2):204-223

An important question in Southwestern archaeological research is how social and economic ties between prehistoric groups changed through time. The chemical and mineralogical matching of stone tools and ceramics to source areas is one approach to addressing this question. Here we challenge the assumption that igneous rocks used for manufacturing stone tools and ceramics in the Mesa Verde region of Colorado were originally derived from the Chuska Mountains of New Mexico. Recent geological surveys suggest that small igneous features present in and around Mesa Verde National Park and Ute Mountain Ute Tribal Park contain similar lithologies and may represent a local source. We systematically visited seven of these igneous exposures and nine downstream gravel deposits, looking for geological sources and quarry sites matching the lithology of analyzed debitage from this region. Our results suggest that the ancestral Puebloans could have procured such igneous rocks as aphanitic minette and trachybasalt pottery temper from local areas. Because the trachybasalt is usually thought to have been imported from the Chuska Mountains, this discovery may require a revision of interpreted trade networks based on pottery temper and lithic raw material distinctions. © 2009 Wiley Periodicals, Inc.  相似文献   

Enriched Sr-Nd Isotopic Characteristics of Amphibolites in the Oki-Dogo Island, Japan: Evidence for Crust-Mantle Interaction by Deeply Subducted Continental Crust     

Yoji Arakawa  Tsugio Kouta  Yasuhide Kanda  Hiroshi Amakawa 《Gondwana Research》2001,4(4):562-563

  相似文献   

悬沙水体不同波段反射比的分布特征及悬沙量估算实验研究   总被引：14，自引：0，他引：14  

博克忖  荒川久幸  曾宪模 《海洋学报》1999,21(3):134-140

我国沿岸、河口附近水域具有高悬沙量的特点.悬沙的分布、扩散、沉降过程影响港口、航道水深的维持,影响生态环境.利用卫星遥感资料开展悬沙遥感及定量算法研究,在我国已取得诸多成果,挥才兴等[1]提出了几种悬沙定量的经验和半经验模式.“七五”攻关分别对黄河口和长江口提出了对数模式、线性分析模式和双峰比模式,Ma等[2]将模式识别方法应用于悬沙遥感.90年代后期,国际上陆续发射多颗海色卫星,我国也计划发射海色卫星,为有效地利用海色卫星资料,进一步开展悬沙定量算法及传感器谱段选择研究具有重要意义.  相似文献