Generation of unsaturated and aromatic hydrocarbons by thermal alteration of young kerogen     

Ryoshi Ishiwatari  Kazuo Fukushima 《Geochimica et cosmochimica acta》1979,43(8):1343-1349

Monounsaturated, monoaromatic and polyaromatic hydrocarbons generated by artificial thermal alteration of young marine (Tanner basin, offshore California) kerogen were studied by computerized GC-MS. Their relative amounts changed with temperature (150–410°C) and time (5–120 hr) of heating as follows: Monounsaturates → Monoaromatics → Polyaromatics. Distribution of alkyl homologs of phenanthrene also changed with increasing degree of thermal alteration. These results are in agreement with those observed for crude oils and shales.  相似文献   

Natural water-purification system observed in a shallow coastal lagoon: Matsukawa-ura,Japan     

Kohata K  Hiwatari T  Hagiwara T 《Marine pollution bulletin》2003,47(1-6):148-154

Field surveys and in situ experiments were conducted in the shallow Matsukawa-ura in summer to evaluate the biological efficiencies of shallow-water areas for preserving coastal ecosystems. In Matsukawa-ura (5.8 km(2)), the suspension-feeding bivalves Ruditapes philippinarum and Crassostrea gigas were the dominant animals--their total biomasses (wet weight) were estimated to be 3.4 x 10(6) and 2.3 x 10(6) kg, respectively. Ulva sp. and Zostera marina were the dominant macrophyte species during the summer, with standing crops estimated to be 0.29 x 10(6) and 0.20 x 10(6) kg, respectively. The dissolved inorganic nitrogen (DIN) uptake rates for Ulva sp. and Z. marina were determined by in situ experiments. An ecological model calculated on the basis of the observed dataset showed that, in comparison with tidal exchange, a significant amount of particulate organic matter was removed by bivalve filtration and a considerable quantity of DIN was removed by macrophyte species.  相似文献   

A VLBI Delay Model for Radio Sources at a Finite Distance     

M. Sekido  T. Fukushima 《Journal of Geodesy》2006,80(3):137-149

A relativistic delay model for Earth-based very long baseline interferometry (VLBI) observation of sources at finite distances is derived. The model directly provides the VLBI delay in the scale of terrestrial time. The effect of the curved wave front is represented by using a pseudo source vector K = (R ₁ + R ₂)/(R ₁ + R ₂), and the variation of the baseline vector due to the difference of arrival time is taken into account up to the second-order by using Halley’s method. The precision of the new VLBI delay model is 1 ps for all radio sources above 100 km altitude from the Earth’s surface in Earth-based VLBI observation. Simple correction terms (parallax effect) are obtained, which can also adopt the consensus model (e.g. International Earth Rotation and Reference Frames Service conventions) to finite-distance radio source at R > 10 pc with the same precision. The new model may enable estimation of distance to the radio source directly with VLBI delay data.  相似文献   

Transformation from Cartesian to Geodetic Coordinates Accelerated by Halley’s Method     

Toshio Fukushima 《Journal of Geodesy》2006,79(12):689-693

By using Halley’s third-order formula to find the root of a non-linear equation, we develop a new iterative procedure to solve an irrational form of the “latitude equation”, the equation to determine the geodetic latitude for given Cartesian coordinates. With a limit to one iteration, starting from zero height, and minimizing the number of divisions by means of the rational form representation of Halley’s formula, we obtain a new non-iterative method to transform Cartesian coordinates to geodetic ones. The new method is sufficiently precise in the sense that the maximum error of the latitude and the relative height is less than 6 micro-arcseconds for the range of height, −10 km ≤ h ≤ 30,000 km. The new method is around 50% faster than our previous method, roughly twice as fast as the well-known Bowring’s method, and much faster than the recently developed methods of Borkowski, Laskowski, Lin and Wang, Jones, Pollard, and Vermeille.  相似文献   

A test of ray theory and scattering theory based on a laboratory experiment using ultrasonic waves and numerical simulation by finite‐difference method     

Jesper Spetzler  Chadaram Sivaji  Osamu Nishizawa  Yo Fukushima 《Geophysical Journal International》2002,148(2):165-178

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Subsidence associated with the LUSI mud eruption,East Java,investigated by SAR interferometry     

Yo Fukushima  Jim Mori  Manabu Hashimoto  Yasuyuki Kano 《Marine and Petroleum Geology》2009

A mud volcano LUSI initiated its eruption on 29 May 2006, adjacent to a hydrocarbon exploration well in East Java. Ground subsidence in the vicinity of the LUSI eruptive vent was well recorded by a Synthetic Aperture Radar (SAR) PALSAR onboard the Japanese ALOS satellite. We apply an Interferometric SAR (InSAR) technique on ten PALSAR data scenes, acquired between 19 May 2006 and 21 May 2007, in order to obtain continuous maps of ground displacements around LUSI. Although the displacements in the area closest to the eruptive vent (spatial extension of about 1.5 km) are not detectable because of the erupted mud, all the processed interferograms indicate subsidence in an ellipsoidal area of approximately 4 km (north–south) × 3 km (east–west), centered at the main eruptive vent. In particular, interferograms spanning the first four months until 4 Oct. 2006 and the subsequent 46 days between 4 Oct. 2006 and 19 Nov. 2006 show at least about 70 cm and 80 cm of displacements away from the satellite, respectively. Possible causes of the subsidence, i.e., 1) loading effect of the erupted mud, 2) creation of a cylindrical mud conduit, and 3) pressure decrease and depletion of materials at depth, are investigated. The effects of the first two causes are found to be insufficient to explain the total amount of subsidence observed in the first six months. The third possibility is quantitatively examined using a boundary element approach by modeling the source of deformation as a deflating oblate spheroid. The spheroid is estimated to lie at depths of a few hundred to a thousand meters. The estimated depths are significantly shallower than determined from analyses of erupted mud samples; the difference is explained by presence of significant amount of inelastic deformation including compaction and downward transfer of material.  相似文献   

Application of spectral decomposition algorithm for mapping water quality in a turbid lake (Lake Kasumigaura,Japan) from Landsat TM data     

Youichi Oyama  Bunkei Matsushita  Takehiko Fukushima  Kazuo Matsushige  Akio Imai 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(1):73-85

The remote sensing of Case 2 water has been far less successful than that of Case 1 water, due mainly to the complex interactions among optically active substances (e.g., phytoplankton, suspended sediments, colored dissolved organic matter, and water) in the former. To address this problem, we developed a spectral decomposition algorithm (SDA), based on a spectral linear mixture modeling approach. Through a tank experiment, we found that the SDA-based models were superior to conventional empirical models (e.g. using single band, band ratio, or arithmetic calculation of band) for accurate estimates of water quality parameters. In this paper, we develop a method for applying the SDA to Landsat-5 TM data on Lake Kasumigaura, a eutrophic lake in Japan characterized by high concentrations of suspended sediment, for mapping chlorophyll-a (Chl-a) and non-phytoplankton suspended sediment (NPSS) distributions. The results show that the SDA-based estimation model can be obtained by a tank experiment. Moreover, by combining this estimation model with satellite-SRSs (standard reflectance spectra: i.e., spectral end-members) derived from bio-optical modeling, we can directly apply the model to a satellite image. The same SDA-based estimation model for Chl-a concentration was applied to two Landsat-5 TM images, one acquired in April 1994 and the other in February 2006. The average Chl-a estimation error between the two was 9.9%, a result that indicates the potential robustness of the SDA-based estimation model. The average estimation error of NPSS concentration from the 2006 Landsat-5 TM image was 15.9%. The key point for successfully applying the SDA-based estimation model to satellite data is the method used to obtain a suitable satellite-SRS for each end-member.  相似文献   

Observations of C2 Molecules in the Coma of Comets at Mitaka     

Sekiguchi  T.  Watanabe  J.  Fukushima  H.  Yamamoto  T.  Yamamoto  N. 《Earth, Moon, and Planets》1997,78(1-3):143-148

In order to monitor the various phenomena of comets, we continuously made the near-nucleus imaging observations of comets at National Astronomical Observatory, Mitaka. Here we report on the results of the observations of two spectacular comets. One is the analysis of photometry of C₂ emission images in the coma of comet Hyakutake (C/1996 B2). By comparing the production rates of C₂ radicals with C₂H₂ molecules, we conclude that the most C₂ radicals were originated from C₂H₂, while some of them might be produced from other parents. The second item is the analysis of the morphology of C₂ emission images in the coma of comet Hale-Bopp(C/1995 O1). By applying a ring masking technique, we detected asymmetrical distribution of the C₂ molecules. The results of these two comets might suggest that a portion of C₂ radicals were formed by the disintegration of the small organic dust grains, like the so-called CHON particles. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

基于InSAR同震形变观测反演2010年新西兰南岛M_w7.1 Darfield地震同震破裂分布          下载免费PDF全文

罗旭巍  孙建宝  沈正康  Yo Fukushima 《地球物理学报》2013,56(8):2613-2624

2010年9月4日新西兰南岛Canterbury平原发生了M_w7.1地震,震源深度约为10 km.本次地震发生在一条震前不为人所知的断层上.我们利用覆盖整个震区的合成孔径雷达(SAR)观测资料,通过干涉处理分析获得雷达视线向(LOS)同震形变场;以此资料为约束反演了断层的几何参数以及同震破裂分布.结果显示,该地震造成四条相对独立断层的破裂.大部分的地震矩释放发生在Greendale断层(编号1-4),其错动以右旋走滑为主,最大破裂约为8.5 m.其它三条断层中,经过震源的逆冲断层最大破裂为5.1 m (编号6),位于Greendale断层以西的逆冲断层最大破裂为3.5 m (编号5),位于Greendale断层北面的走滑断层最大破裂为1.9 m(编号7).反演的Greendale断层地表滑动与地质调查得到的地表破裂在形态和数值上均吻合较好.本次地震释放的地震矩为5.0×10¹⁹N·m,矩震级为7.1.板块边界带形变场分析表明,Darfield地震的发生受边界带应变分配在该地区残留构造应力场控制,其复杂性体现了区域构造应力场的特点.地震对其周围地区的应力场影响较大,库仑应力增加区与余震分布有一定对应关系,并在2011年Christchurch 6.3级地震发震断层区域造成约0.1bar的库仑应力增加,对此地震有一定的触发作用.  相似文献   

The IAU 2009 system of astronomical constants: the report of the IAU working group on numerical standards for Fundamental Astronomy     

Brian Luzum  Nicole Capitaine  Agn??s Fienga  William Folkner  Toshio Fukushima  James Hilton  Catherine Hohenkerk  George Krasinsky  G??rard Petit  Elena Pitjeva  Michael Soffel  Patrick Wallace 《Celestial Mechanics and Dynamical Astronomy》2011,110(4):293-304

In the 2006?C2009 triennium, the International Astronomical Union (IAU) Working Group on Numerical Standards for Fundamental Astronomy determined a list of Current Best Estimates (CBEs). The IAU 2009 Resolution B2 adopted these CBEs as the IAU (2009) System of Astronomical Constants. Additional work continues to define the process of updating the CBEs and creating a standard electronic document.  相似文献