Eigenvalues and eigenvectors for hybrid coordinate equations of motion for flexible spacecraft     

Yoshiaki Ohkami  Peter Likins 《Celestial Mechanics and Dynamical Astronomy》1979,19(4):359-390

Literal characterizations are developed for the eigenvalues and eigenvectors of a system of linear time-invariant equations which describes the attitude motion of flexible spacecraft in terms of hybrid coordinates. The eigenproblem is shown to reduce to that of a symmetric and positive definite matrix of lower dimension. For the zero damping case, both analytical and minimax characterization methods prove to be useful in localizing the eigenvalues, and eigenvectors for systems of large dimension are obtained explicitly in terms of a 3×1 matrix whose elements are available from a system of three algebraic equations provided.  相似文献   

Large strain analysis of some geomechanics problems by the finite element method     

Yoshiaki Yamada  Abdalla S. Wifi 《国际地质力学数值与分析法杂志》1977,1(3):299-318

This paper presents a rational approach to the finite strain analysis of elastic-plastic materials. An updated incremental finite element technique was applied to problems of shallow foundations of homogeneous as well as multilayer soils. This was based on a variational principle which is suitable for such problems.  相似文献   

Pan-African Alkali Granitoids from the Sør Rondane Mountains, East Antarctica     

Zilong Li  Yoshiaki Tainosho  Jun-ichi Kimura  Kazuyuki Shiraishi  Masaaki Owada 《Gondwana Research》2003,6(4):595-605

Alkali granitoids (500-550 Ma) representing a prominent Pan-African magmatic event are widely distributed in the Sør Rondane Mountains, Dronning Maud Land, East Antarctica. Geochemically, they are granitic to syenitic in composition and show an alkaline affinity of A-type granites. They are characterized by high K₂O+Na₂O (7-13 wt%) and K₂O/Na₂O (1-2), low to intermediate Mg#, wide ranges of SiO₂ (45-78 wt%), Sr (20-6500 ppm) and Ba (40-13000 ppm) and have Nb and Ti depletion in the primitive mantle normalized diagram. The granitoids are subdivided into Group I granites, Group II granites, Lunckeryggen Syenitic Complex and Mefjell Plutonic Complex. The Group I granites have higher Mg#, Sr/Ba, Sr/Y, (La/Yb)_N and LREE/HREE, lower A/CNK, SREE and initial ⁸⁷Sr/⁸⁷Sr ratios and lack Eu anomalies compared to those with negative Eu anomalies in the Group II granites. The syenitic rocks from the Mefjell Plutonic Complex are higher in alkali, Ga, Zr, Ba, and have lower Mg#, Rb, Sr, Nb, Y, F and LREE/HREE with positive Eu anomaly, whereas the granites from the Mefjell Plutonic Complex have high LREE/HREE ratios with negative Eu anomaly. The Lunckeryggen syenitic rocks have intermediate Mg#, higher K₂O, P₂O₅, TiO₂, Fe₂O₃/FeO, Ba, Sr/Y and LREE/HREE ratios with lack of Eu anomalies and are lower in Al₂O₃, Ga, Y, Nb and Rb/Sr ratios. Based on chemical characteristics combined with isotopic data, we suggest that the Lunckeryggen syenitic body and Group I granitic bodies may be derived from the mantle-derived hot basic magma by fractional crystallization with minor assimilation. We also suggest that the Group II granites may be derived from assimilation with crustal rocks to varing degrees and then fractional crystallization in higher crustal levels (ACF model). The Mefjell Plutonic Complex seems to be derived from a heterogenetic magma source compared with other granitoids from the Sør Rondane Mountains. The syenitic rocks in the Mefjell Plutonic complex have a unique source (iron-enriched) and have a chemical affinity with the charnockites in Gjelsvikjella and western Mühlig-Hofmannfjella, but not like the Yamato syenites in adjacent areas.  相似文献   

Far-Field Tsunami Potential and a Real-Time Forecast System for the Pacific Using the Inversion Method   总被引：1，自引：0，他引：1  

Koike  Nobuaki  Kawata  Yoshiaki  Imamura  Fumihiko 《Natural Hazards》2003,29(3):425-436

Estimating tsunami potential is anessential part of mitigating tsunami disasters. Weproposed a new method to estimate the far-fieldtsunami potential by assuming faultmodels on the Pacific Rim. We find thata tsunami that generates in the areas wherethere is no tsunami in the history can damagethe Japanese coast. This shows that it isimportant to estimate tsunami potential byassuming fault models other than the pastearthquake data.Another important activity to mitigate tsunamidisasters is to provide appropriatewarnings to coastal communities when dangerfrom a tsunami is imminent. We applied anew inversion method using wavelet transformto a part of the real-time tsunami forecastsystem for the Pacific. Because this inversionmethod does not require fault location, it ispossible to analyze a tsunami in real timewithout all seismic information. In order tocheck the usability of the system, anumerical simulation was executed assuming anearthquake at sea off Taiwan. The correlationcoefficient for the estimated initialwaveform to the assumed one was calculatedto be 0.78. It takes 90 min to capturetime-series waveform data from tsunamigauges and 5 sec to estimate the 2-D initialwaveform using the inversion method. After that,it takes 2 minutes to forecast thetsunami heights at the Japanese coast. Since thesum of these times is less than the 105minutes transit time of the tsunami fromTaiwan to Japan, it is possible to give a warningto the residents before the tsunami attacksthe Japanese coast. Comparing the tsunamiheights forecasted by this system with thosecalculated by the fault model, the averageerror was 0.39 m. The average error ofthe arrival time was 0.007 min.  相似文献   

Map projection errors in the Weber problem     

Yoshiaki Ohsawa  Hirofumi Kagaya  Takeshi Koshizuka 《Journal of Geographical Systems》2002,4(3):325-342

 When demand points are given as a planar map where projection method is explicitly stated, we usually know the latitudes and longitudes of these points from the map. Then we can solve the Weber problem on the globe, and we do not suffer from errors. This paper analyses how cylindrical projections cause distortion in the Weber problem when demands are distributed on the Northern Hemisphere. First, we demonstrate that planar solutions are always located south of the spherical solution if the Mercator projection, the equirectangular projections with standard parallels near the demands, or the equal-area projection with the same characteristic is chosen. Second, we verify that this geographical tendency is inclined to hold when the demand points, are distributed symmetrically, widely or toward the north. Received: 15 August 2001 / Accepted: 20 April 2002 This paper was partially written while the first author was visiting the Department of Geography at the Catholic University of Louvain, Louvain-la-Neuve, Belgium [1993–1994]. He is grateful for the hospitality of this department. An earlier version of this paper was presented in 1994 at the Seventh Meeting of the European Operational Research Working Group on Locational Analysis in Brussels, and in 1996 at the Fifth World Congress of the Regional Science Association International in Tokyo. The authors would also like to thank the participants as well as three anonymous referees for their constructive comments.  相似文献   

Stress-induced crack path in Aji granite under tensile stress     

Yozo Kudo  Osam Sano  Naokuni Murashige  Yoshiaki Mizuta  Koji Nakagawa 《Pure and Applied Geophysics》1992,138(4):641-656

The double-torsion test using Aji granite was carried out to investigate the interaction between stress-induced crack path and mineral grains. Crack velocities were controlled at range 10^–7 m/s to 10^–1 m/s. After the stressed specimens were dyed, we checked the crack path by thin section analysis, using an optical microscope. The stress-induced crack path was divided into two types, transgranular and intergranular cracks, and each path was subdivided with respect to mineral grains. In spite of the extensive range of crack velocities, the ratios between the transgranular and intergranular crack lengths did not change. The crack paths were all jagged, and often showed detour around the grain boundary when faced with obstacles like hard grains or preexisting cracks. That is to say, quartz grain played an important role as an obstacle. Feldspar grain could change the crack path because of its cleavage plane. Biolite grain had a serious effect on the path even if its constitution ratio is very small. Fractal dimensions of the crack paths were calculated by three methods, as indicators of surface roughness. The fractal dimensions were shown in a slight trend with the change of crack velocity. This trend can be explained from the point of limited cracking rate in stress corrosion.  相似文献   

Low frequency electrical impedance of partially molten gabbro: The effect of melt geometry on electrical properties     

Hiroki Sato  Yoshiaki Ida 《Tectonophysics》1984,107(1-2)

Electrical impedance of partially molten gabbro was measured as a function of the frequency of the applied electric field. The impedance of the partially molten gabbro was mainly controlled by the volume and geometry of partial melt, which were observed with an optical microscope study of the quenched sample. The experimental results are interpreted by a theory that formulates the electrical property of rocks containing partial melt, taking ionic diffusion in the melt into account. The theory evaluates the contributions from two types of melt-geometry distributed in the rock matrix, namely:

1. (a) nearly isolated melt pockets, and

2. (b) connected melt along grain boundaries.

According to the theory, connected melt mainly contributes to the increase of net conductivity, while melt pockets increase displacement current and cause the frequency dependence of impedance. The characteristic ionic diffusivity in melt pockets was determined from the peak frequency of the imaginary part of impedance. The magnitude of diffusion coefficient is estimated to be of the order of 10⁻⁷ to 10⁻⁶ cm²/sec. This suggests that sodium, iron, magnesium and/or calcium ions mainly carry the electric charge in partial melt. The observed frequency dependence of impedance is considered to reflect ionic polarization in melt pockets due to the migration of these alkali ions toward solid-melt interfaces.The present experimental and theoretical work suggests that electrical properties of the earth's upper mantle may involve an intrinsic frequency dependence associated with ionic diffusion in the frequency range of geomagnetic observation, if a partial melt zone exists. The analysis of the earth's conductivity structure may be inadequate if such intrinsic frequency dependence of mantle media is neglected.  相似文献   

Fine structure of laboratory wind-wave surfaces studied using an optical method     

Naoto Ebuchi  Hiroshi Kawamura  Yoshiaki Toba 《Boundary-Layer Meteorology》1987,39(1-2):133-151

The fine structure of laboratory wind-wave surfaces was investigated using an optical method. Several characteristic structures, closely associated with wind speed and the stage of development of the waves, are described. A parallel light, incident on the wind-wave surface, was backscattered by specular facets perpendicular to the incident angle. These specular facets, which represented the fine structures, were photographed and quantitatively analyzed by image processing techniques.For wind speeds ranging from 3.6 to 13.6 m s^–1, different types of small-scale undulations appeared: a three-dimensional rhombic structure; a train of capillary waves on the forward face with wavelengths gradually decreasing with distance from the crest, and a streaky structure on the backward face in the direction of the wind; and random and wide-spreading irregularities covering the whole wind-wave surface. The spatial scales and temporal variation of the undulations are described.  相似文献   

Differential Fractionation of Rare Earth Elements in Oxidized and Reduced Granitic Rocks: Implication for Heavy Rare Earth Enriched Ion Adsorption Mineralization          下载免费PDF全文

Yasushi Watanabe  Yoshiaki Kon  Takuya Echigo  Atsushi Kamei 《Resource Geology》2017,67(1):35-52

Ion adsorption rare earth element (REE) deposits in southern China are the exclusive source of heavy REEs (HREEs) in the world, and this HREE‐enriched character of the deposits is inherited from the REE compositions of the underlying granitic rocks. Such HREE‐enriched rocks form from heavy fractionation of reduced granitic magmas. We explore why reduced granitic magmas are enriched in HREEs during the fractionation, based on the REE geochemistry of granitic rocks and abundance of REEs in their constituent minerals in the southwestern Japan arc of Cretaceous to Paleogene age. The compilation of the whole rock geochemistry and REE compositions of the granitic rocks of the Sanin (oxidized), Sanyo (reduced) and Ryoke (reduced) belts in the southwestern Japan arc indicates that: (i) light REEs (LREEs) decease with fractionation of the granitoids in the Sanin belt but this trend is not clear in the granitoids in the Sanyo belt and LREEs rather increase in the Ryoke granitoids; (ii) Eu decreases with fractionation in all the belts; and (iii) HREEs slightly, but steadily decrease in the Sanin belt but enrich significantly in the Sanyo and Ryoke belts with fractionation. Analytical results of REE concentrations by scanning electron microscope with energy dispersive X‐ray spectroscope and laser ablation‐inductively coupled plasma mass spectrometer in the constituent minerals in a granodiorite sample from the Sanin belt show a moderate concentration of REEs in hornblende (577 ppm) in addition to high concentrations in allanite (~20 %), britholite (~30 %), primary titanite (8922 ppm), apatite (4062 ppm), and zircon (1693 ppm). Because primary titanite and allanite are commonly present in the oxidized granitoids but not in the reduced ones, the REE depletion in the fractionated, oxidized granites is attributed to the crystallization of these minerals. In contrast, scarcity of these minerals in the reduced granitoids enriches REEs, in particular HREEs in the fractionated magmas, which finally precipitate REEs in the granites and pegmatites. Both positive, but different correlation ratios between the Nb and Dy concentrations in the granitoids of the Sanin and Sanyo‐Ryoke belts suggest that columbite–pyrochlore‐group and fergusonite‐group minerals are the major HREE host in the oxidized and reduced granites, respectively.  相似文献   

Unusual behavior of the Kuroshio Current System from winter 1996 to summer 1997 revealed by ADEOS-OCTS and other data— Suggestion of topographically forced alternating-jet instability     

Yoshiaki Toba  Hiroshi Murakami 《Journal of Oceanography》1998,54(5):465-478

While the Advanced Earth Observing Satellite (ADEOS) was operating, the Kuroshio and the Kuroshio Extension, or the Kuroshio Current System, exhibited unusual behavior from the winter of 1996 to the summer of 1997. This behavior of the Kuroshio Current System has been closely studied using a time series of satellite observation images of SST and ocean color obtained by ADEOS-OCTS, reinforced by SST images obtained by NOAA-AVHRR. Our findings include (i) a long lasting, very southerly path of the Kuroshio Extension; (ii) a Kuroshio path very distant from Japan with the following alternating-jet-like north-south flow pattern of the Kuroshio Extension, which occurred twice, once in February and once in April 1997, as independent events and which was observed to be affected by the bottom topography of the Izu-Ogasawara Ridge and Trench, and of the Japan Trench; (iii) cutting off of a cold water mass after the February event; and (iv) the formation of a vortex pair after the April event. A new mechanism is suggested for the formation of the alternating-jet flow pattern: a topographically forced alternating-jet instability (AJI). An SST-Chlorophyll Diagram (T-Chl Diagram) generated using simultaneous data from a single satellite is useful for analyzing the water mass structure of this region, including biological processes.  相似文献