Olivine-rich exposures in the South Pole-Aitken Basin     

Satoru Yamamoto  Ryosuke Nakamura  Tsuneo Matsunaga  Yoshiko Ogawa  Yoshiaki Ishihara  Tomokatsu Morota  Naru Hirata  Makiko Ohtake  Takahiro Hiroi  Yasuhiro Yokota  Junichi Haruyama 《Icarus》2012,218(1):331-344

The distribution and the geological context of the olivine-rich exposures in the South Pole-Aitken (SPA) Basin on the Moon were investigated based on the spectral data obtained from the Spectral Profiler (SP) and Multiband Imager (MI) onboard the Japanese lunar explorer Kaguya/SELENE. The olivine-rich exposures are found only in the peak rings or central peaks of the Schrödinger basin and Zeeman crater, which are located in the outer region of the SPA Basin and not in the center region. On a localized scale, the olivine-rich materials are exposed on landslide features on the crater walls or sloped wall of the central peaks or the peak rings. Another observational finding is the co-existence of olivine-rich and plagioclase-rich materials on a kilometer scale spanning most of the olivine-rich sites in the Schrödinger basin. Pyroxene-rich materials are found in fresh craters outside the peak rings or the central peaks with olivine-rich materials. Based on these results, the following scenario are proposed: (1) the impact to form the SPA Basin melted a large amount of the lunar upper mantle and crust, and distributed the melted materials to the outer region; (2) local differentiation of melted materials hid the olivine-rich materials in the center region of the SPA Basin; (3) later impacts that formed the Schrödinger and Zeeman craters excavated and exposed the olivine-rich materials to the surface again; and (4) space weathering and regolith gardening obscured the olivine-rich spectra at the exposure sites, but recent, small scale impacts or landslides on the sloped wall exposed fresh olivine-rich materials, allowing the identification of the olivine-rich exposures by spectral remote-sensing. This suggests that several, different scale events play an important role in forming the surface distributions of originally deep-seated materials on the Moon, as well as on other planetary bodies.  相似文献   

Revisiting ocean thermal energy conversion   总被引：1，自引：0，他引：1  

Rod Fujita  Alexander C. Markham 《Marine Policy》2012,36(2):463-465

Increasing concerns regarding oil spills, air pollution, and climate change associated with fossil fuel use have increased the urgency of the search for renewable, clean sources of energy. This assessment describes the potential of Ocean Thermal Energy Conversion (OTEC) to produce not only clean energy but also potable water, refrigeration, and aquaculture products. Higher oil prices and recent technical advances have improved the economic and technical viability of OTEC, perhaps making this technology more attractive and feasible than in the past. Relatively high capital costs associated with OTEC may require the integration of energy, food, and water production security in small island developing states (SIDSs) to improve cost-effectiveness. Successful implementation of OTEC at scale will require the application of insights and analytical methods from economics, technology, materials engineering, marine ecology, and other disciplines as well as a subsidized demonstration plant to provide operational data at near-commercial scales.  相似文献   

Formation age of the lunar crater Giordano Bruno     

Tomokatsu Morota  Junichi Haruyama  Hideaki Miyamoto  Chikatoshi Honda  Makiko Ohtake  Yasuhiro Yokota  Tsuneo Matsunaga  Naru Hirata  Hirohide Demura  Hiroshi Takeda  Yoshiko Ogawa  Jun Kimura 《Meteoritics & planetary science》2009,44(8):1115-1120

Abstract— Using the Terrain Camera onboard the Japanese lunar explorer, SELENE (Kaguya), we obtained new high‐resolution images of the 22‐kilometer‐diameter lunar crater Giordano Bruno. Based on crater size‐frequency measurements of small craters (<200 m in diameter) superposed on its continuous ejecta, the formation age of Giordano Bruno is estimated to be 1 to 10 Ma. This is constructive evidence against the crater's medieval age formation hypothesis.  相似文献   

Precise estimation of hourly global solar radiation for micrometeorological analysis by using data classification and hourly sunshine     

Yoshimitsu Masaki  Tsuneo Kuwagata  Yasushi Ishigooka 《Theoretical and Applied Climatology》2010,100(3-4):283-297

We have developed a method for estimating hourly global solar radiation (GSR) from hourly sunshine duration data. This procedure requires only hourly sunshine duration as the input data and utilizes hourly precipitation and daily snow cover as auxiliary data to classify time intervals into six cases according to weather conditions. To obtain hourly GSR using a simple algebraic form, a quadratic function of the solar elevation angle and the sunshine duration ratio is used. Daily GSR is given by a sum of hourly GSRs. We evaluated the performance of the newly developed method using data obtained at 67 meteorological stations and found that the estimated GSR is highly consistent with that observed. Hourly and daily root-mean-square misfits are approximately 0.2 MJ/m²/h (~55 W/m²) and 1.4 to 1.5 MJ/m²/day (~16 to 17 W/m²), respectively. Our classification of weather conditions is effective for reducing estimation errors, especially under cloudy skies. Since the sunshine duration is observed at more meteorological stations than GSR, the proposed new method is a powerful tool for obtaining solar radiation with hourly resolution and a dense geographical distribution. One of the proposed methods, GSRgrn, can be applicable to hourly GSR estimations at different observation sites by setting local parameters (the precipitable water, surface albedo, and atmospheric turbidity) suitable to the sites. The hourly GSR can be applied for various micrometeorological studies, such as the heat budget of crop fields.  相似文献   

利用ASTER数据估算2002年4月阿克苏地表特征和植被参数   总被引：1，自引：1，他引：0  

马伟强  马耀明  胡泽勇  仲雷  李茂善  赵逸舟  王永杰  王介民 《高原气象》2008,27(3):544-550

利用ASTER卫星可见光和短波红外波段数据,估算了2002年4月12日阿克苏地区地表特征参数(地表温度T、地表反射率α)和植被参数(归一化植被指数NDVI、修正的土壤调整植被指数MSA-VI、植被覆盖度Pv和叶面积指数LAI等)。结果表明,各种植被参数在沙漠地区较小,而在绿洲中的值较大。同时本文认为ASTER遥感数据有较高的地面分辨率,利用它可以更好地反映地表的植被参数及地表特征参数状况;还指出了ASTER卫星数据在沙漠绿洲中的适用性。  相似文献   

Horizontal displacements in Japan     

Naomi Fujita 《Tectonophysics》1974,23(4):419-422

Recent horizontal displacements in Japan are discussed by using the results of the first-order triangulation surveys. Large horizontal displacements are found in East Hokkaido, Tohoku, South Kanto, Tokai and Nankai districts (Fig.1). Crustal activity in these districts is also briefly discussed. The original triangulation survey in Japan neglected Laplace (azimuth) observations and consequently rotation and divergence around the assumed fixed point often appear as horizontal displacements. This is especially true in the central Japan where horizontal displacements result from cancelling the apparent rotation and divergence around the assumed fixed point (Fig.2).On the other hand, strain measurements avoid such shortcoming. Considering with the results of the first triangulation, the horizontal earth-strain can be calculated for every subsequent triangulation net. It is interesting that the velocity of the maximum shear strain is almost 2–3 · 10^/t7/year throughout Japan (Fig.3), even though the seismic activities show large regional discrepancies.  相似文献   

Basic theory of three-dimensional landslide modeling based on the logical model of geologic structure     

A. Kajiyama  K. Shiono  S. Masumoto  T. Fujita 《Landslides》2005,2(3):212-220

Dynamic visualization of landslide cross-sections is important for understanding the structure and mechanism of landslide formation. Moreover, the modeling of geologic information plays an effective role in geo-hazard assessment and their mitigation. In this study, we developed the basic theory of a three-dimensional landslide modeling and applied it to the Nigawa landslide of the Hyogo Prefecture in central Japan. The construction of this model is based on the boundary surfaces of slump blocks and geologic units, and the hierarchical relationships between these surfaces. An application algorithm was validated and the model proved efficient in depicting the nature of landslides in the Nigawa area.  相似文献   

Observation and numerical analysis of soil-structure interaction of a reinforced concrete tower     

Todor Ganev  Fumio Yamazaki  Tsuneo Katayama 《地震工程与结构动力学》1995,24(4):491-503

A vast amount of earthquake response records of an observation tower are used together with microtremor data to investigate various aspects of the dynamic behaviour of the soil-structure system. It is found that separation of the soil from the structure occurs under large dynamic loads, leading to changes in the predominant frequency of the system. As a result of the decreasing of the soil support at the side walls of the foundation, the stress caused by the structural weight on the bottom soil increases during earthquakes. With regard to its practical applicability, a linear sway-rocking model is applied for numerical modelling of the soil-structure system. Alterations in the soil support as a result of soil non-linearity and separation of the structure from the soil are investigated by comparing recorded and simulated structural response. The influence of each of these factors on the softening of the soil support is distinctly assessed. An empirical relationship between the peak ground velocity and the soil constants for earthquake excitations of different magnitude is presented.  相似文献   

Seismicity and tectonics of the far Western Aleutian Islands     

James T. Newberry  David L. Laclair  Kazuya Fujita 《Journal of Geodynamics》1986,6(1-4)

Study of focal mechanisms of earthquakes in the Near and Komandorsky Islands indicate that there are several distinct zones of tectonic activity. South of the Near Islands, normal faulting occurs in the trench east of 172°E and low-angle thrusting dominates the Aleutian ridge. Mechanisms indicate underthrusting as far west as Mednyy Island with strike-slip faulting restricted to the south and west of Beringa Island. A zone of northeast striking left-lateral faulting near 1645.°E is proposed to separate the Aleutian Ridge from Kamchatka Peninsula. This motion, as well as faulting north of the Komandorsky Islands, may be related to the existance of a buffer plate comprising the Aleutian Ridge in the Komandorsky Islands. Active subduction terminates near 173°E and the faulting north of the Komandorsky Islands may, in part, be due to the bouyancy of a remnant slab. Depth phase modelling indicates bulletin-reported depths are overestimated due to a misidentification of depth phases.  相似文献   

Present-day plate interactions in Northeast Asia: North American, Eurasian, and Okhotsk plates     

David B Cook  Kazuya Fujita  Cindy A McMullen   《Journal of Geodynamics》1986,6(1-4)

Based on seismicity and focal mechanisms, a separate Okhotsk plate is identified which includes most of the Sea of Okhotsk, Kamchatka Peninsula, and the Suntar-Khayata Mountains, in the northeastern USSR. Using slip vectors from the largest earthquakes in the region, we obtain a North America-Eurasia pole of rotation near the Lena River delta and a Okhotsk-North America pole off western Chukotka. The computed poles satisfy observed thrust faulting mechanisms in the northern Cherskii Mountains which are discordant with models proposed by previous workers. It is suggested that the Arctic rift propagated through northeast Siberia to the Pacific, separating the Okhotsk plate and causing a recent (<3Ma) change in location of the North America-Eurasia pole of rotation.  相似文献