The carbon isotopic ratio of atmospheric carbon dioxide at Tsukuba,Japan   总被引：1，自引：0，他引：1  

Hisayuki Inoue  Yukio Sugimura 《Journal of Atmospheric Chemistry》1985,2(4):331-344

To find out the secular and seasonal trends of the ¹³C value and CO₂ concentration in the surface air and the determination of the ¹³C in the atmospheric CO₂ collected at Tsukuba Science City was carried out during the period from July 1981 to October 1983. The monthly average of the ¹³C value of CO₂ in the surface air collected at 1400 LMT ranged from -7.52 to \s-8.45 with an average of -7.96±0.25 and the CO₂ concentration in the air varied from 334.5 l 1^-1 to 359 l 1^-1 with an average of 347.2±6.3 l 1^-1. The ¹³C value is high in summer and low in winter and is negatively correlated with the CO₂ concentration. In general, the relationship between the ¹³C and the CO₂ concentration is explainable by a simple mixing model of two different constant carbon isotopic species but the relationship does not always follow the model. The correlation between the ¹³C value and the CO₂ concentration is low during the plant growth season and high at other times. The observed negative deviation of the ¹³C value from the simple mixing model in the plant growth season is partly due to the isotopic fractionation process which takes place in the land biota.  相似文献   

On the coefficient of shear diffusion     

Yukio Oonishi  Hideaki Kunishi 《Journal of Oceanography》1977,33(3):165-167

The approximate relation of the coefficient of shear diffusion against time is shown by means of a two-level model.  相似文献   

Laboratory Experiment of Plasma Flow Around Magnetic Sail     

Ikkoh Funaki  Hidenori Kojima  Hiroshi Yamakawa  Yoshinori Nakayama  Yukio Shimizu 《Astrophysics and Space Science》2007,307(1-3):63-68

To propel a spacecraft in the direction leaving the Sun, a magnetic sail (MagSail) blocks the hypersonic solar wind plasma flow by an artificial magnetic field. In order to simulate the interaction between the solar wind and the artificially deployed magnetic field produced around a magnetic sail spacecraft, a laboratory simulator was designed and constructed inside a space chamber. As a solar wind simulator, a high-power magnetoplasmadynamic arcjet is operated in a quasisteady mode of 0.8 ms duration. It can generate a simulated solar wind that is a high-speed (above 20 km/s), high-density (10¹⁸ m⁻³) hydrogen plasma plume of ∼0.7 m in diameter. A small coil (2 cm in diameter), which is to simulate a magnetic sail spacecraft and can obtain 1.9-T magnetic field strength at its center, was immersed inside the simulated solar wind. Using these devices, the formation of a magnetic cavity (∼8 cm in radius) was observed around the coil, which indicates successful simulation of the plasma flow of a MagSail in the laboratory.  相似文献   

Characterization of low-temperature pyroclastic surges that occurred in the northeastern Japan arc during the late 19th century     

Akihiko Fujinawa  Masao Ban  Tsukasa Ohba  Kazuo Kontani  Kotaro Miura 《Journal of Volcanology and Geothermal Research》2008

Three eruption events occurring in the central part of the northeastern Japan arc were investigated and compared: Adatara AD1900, Zao AD1895, and Bandai AD1888. Producing low-temperature (LT) pyroclastic surges, these events are characterized by steam eruptions ejecting no juvenile material. These eruptions' well-preserved eruptive deposits and facies facilitated granulometric analyses of the beds, which revealed the transport and deposition mechanisms of LT surges. Combining these results with those of investigations of documents reporting the events, we correlated each eruption to the relevant individual bed and reconstructed the LT surge development sequence. Important findings related to the transport and deposition modes are the following. (1) Bed sets consisting of thin, laminated ash and its overlying thick massive tuff were recognized in the Adatara 1900 proximal deposits. The bed set was probably produced by a strong wind that discharged and propagated quickly from the vent (leading wind) and a gravitationally segregated, highly concentrated flow originated from the eruption column, within a discrete eruption episode. A similar combination might have occurred during the first surge of the Bandai 1888 event. (2) Comparison of the proximal and distal facies for the largest eruption of Adatara 1900 event indicates that the initial turbulence of the eruption cloud decreased rapidly, transforming into a density-stratified surge with a highly concentrated part near the base. Similar surges occurred in the climatic stage of Zao 1895. (3) Bandai 1888 ejecta indicate massive beds deposited preferentially at topographic lows. Co-occurring planar beds showed no topographic affection, as indicated by the topographic blocking of a stratified surge. The observed facies–massive tuffs, crudely stratified tuffs, and thin bedded tuffs–are compatible with those for high-temperature surges. At Bandai, absence of dune bedded tuffs and commonly poorer sorting in the LT surge deposits might be attributable to poor thermally induced turbulence of eruption columns. Condensation of vapor in the surges might have contributed to the poor sorting. The estimated explosion energies were 6 × 10¹³ J for Adatara AD1900, 6.5 × 10¹⁰ J for Zao AD1895, and 6.5 × 10¹⁵ J for Bandai AD1888, implying that the three events were hydrothermal eruptions with distinctive eruptive mechanisms. Regarding eruption sources, the Adatara 1900 event was caused solely by thermal energy of the hydrothermal fluid, although magma intrusion likely triggered evolution of hydrothermal systems at Zao in 1895. Steam eruptions in the Bandai 1888 event occurred simultaneously with sudden exposure of the hydrothermal system, whose triggers require no internal energy.  相似文献   

Editorial to OFES special issue of Ocean Dynamics     

Yukio Masumoto  Hideharu Sasaki  Jin-Song von Storch 《Ocean Dynamics》2010,60(3):631-632

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A note of thanks     

M. I. El-Sabh  Y. Fujinawa  G. Schneider 《Natural Hazards》1989,1(4):401-401

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Microearthquakes along the back-arc spreading system in the eastern Bismarck Sea     

T. Eguchi  Y. Fujinawa  M. Ukawa  L. Bibot 《Geo-Marine Letters》1987,6(4):235-240

OBS's were deployed for 26 to 29 days in the eastern Bismarck Sea to investigate the back-arc spreading. Hypocenters of 186 shallow earthquakes were determined using P- and S-waves from at least five stations. In the western survey area, a transform fault zone is marked by a linear micro-earthquake activity striking N65°W and less than 5 km wide. The predominant type of their focal mechanisms is strike-slip. In the eastern area, several intermittent zones of micro-earthquakes and their strike-slip type focal mechanisms suggest the location of short-length transform faults separating en-echelon spreading ridges.  相似文献   

Measuring geographic segregation: a graph-based approach     

Seong-Yun Hong  Yukio Sadahiro 《Journal of Geographical Systems》2014,16(2):211-231

Residential segregation is a multidimensional phenomenon that encompasses several conceptually distinct aspects of geographical separation between populations. While various indices have been developed as a response to different definitions of segregation, the reliance on such single-figure indices could oversimplify the complex, multidimensional phenomena. In this regard, this paper suggests an alternative graph-based approach that provides more detailed information than simple indices: The concentration profile graphically conveys information about how evenly a population group is distributed over the study region, and the spatial proximity profile depicts the degree of clustering across different threshold levels. These graphs can also be summarized into single numbers for comparative purposes, but the interpretation can be more accurate by inspecting the additional information. To demonstrate the use of these methods, the residential patterns of three major ethnic groups in Auckland, namely Māori, Pacific peoples, and Asians, are examined using the 2006 census data.  相似文献   

Event pattern analysis: Spatial clustering of sequential events and temporal change of events over time     

Yukio Sadahiro 《Transactions in GIS》2023,27(1):260-274

This article develops a method for analyzing spatial and temporal event patterns. Events in this article refer to zero-dimensional objects in the spatiotemporal dimension, which represent the occurrence of crimes, traffic accidents, earthquakes, and so forth. The spatial clustering of sequential events and the increase and decrease in events over time are discussed. These patterns are often observed and analyzed in various academic fields, such as criminology, epidemiology, and geography. However, analytical methods for these patterns have not yet been fully developed. To fill the research gap, this article proposes a new method for analyzing these event patterns. Two statistical measures are utilized, one represents the degree of the spatial clustering of sequential events, and the other evaluates the increase and decrease of events over time. The method is applied to the analysis of the spatial and temporal patterns of the openings of new shops and restaurants in Shibuya-ku, Tokyo. The results gave us interesting empirical findings and indicated the soundness of the method.  相似文献   

饱和珊瑚砂液化特性动三轴试验研究          下载免费PDF全文

郭舒洋  崔杰  吴杨  单毅  中田幸男  梶山慎太郎 《地震工程学报》2024,(1):84-94

为调查饱和珊瑚砂液化相关特性与发展规律,针对饱和Chibishi珊瑚砂,开展一系列不排水循环三轴试验,研究相对密度D_r和循环应力比CSR对饱和Chibishi珊瑚砂的超孔隙水压力Δu、轴向应变ε_a及动强度特性的影响,并分析不同地区珊瑚砂抗液化强度的差异性。结果表明,饱和Chibishi珊瑚砂的Δu发展模式根据不同的CSR水平可以分为前期均匀增长型、前期突增型和后期突增型;此外,采用一种新的孔压模型对前期均匀增长型、前期突增型的孔压比r_u进行表征,Chibishi珊瑚砂在相同的D_r条件下,双幅应变ε_DA达到5%的循环次数N随着CSR水平的增加而逐渐减小;各珊瑚砂在同一里氏震级对应的等效循环振动次数下,抗液化强度CRR的增长模式存在显著差异。研究结果可丰富对珊瑚砂液化特征的认知,同时对近岸和沿海工程的抗震设计提供参考依据。  相似文献