Biogeochemical simulation of microbially induced calcite precipitation with Pararhodobacter sp. strain SO1     

Akiyama  Masaru  Kawasaki  Satoru 《Acta Geotechnica》2019,14(3):685-696

Acta Geotechnica - Biogrouting is a ground improvement technique, which utilizes microorganisms. The numerical simulation of biogrouting is important to ensure efficient operation and to assess the...  相似文献   

Landslide susceptibility mapping of the Sera River Basin using logistic regression model   总被引：2，自引：1，他引：1  

Nussaïbah B. Raja  Ihsan Çiçek  Necla Türkoğlu  Olgu Aydin  Akiyuki Kawasaki 《Natural Hazards》2017,85(3):1323-1346

Of the natural hazards in Turkey, landslides are the second most devastating in terms of socio-economic losses, with the majority of landslides occurring in the Eastern Black Sea Region. The aim of this study is to use a statistical approach to carry out a landslide susceptibility assessment in one area at great risk from landslides: the Sera River Basin located in the Eastern Black Sea Region. This paper applies a multivariate statistical approach in the form of a logistics regression model to explore the probability distribution of future landslides in the region. The model attempts to find the best fitting function to describe the relationship between the dependent variable, here the presence or absence of landslides in a region and a set of independent parameters contributing to the occurrence of landslides. The dependent variable (0 for the absence of landslides and 1 for the presence of landslides) was generated using landslide data retrieved from an existing database and expert opinion. The database has information on a few landslides in the region, but is not extensive or complete, and thus unlike those normally used for research. Slope, angle, relief, the natural drainage network (including distance to rivers and the watershed index) and lithology were used as independent parameters in this study. The effect of each parameter was assessed using the corresponding coefficient in the logistic regression function. The results showed that the natural drainage network plays a significant role in determining landslide occurrence and distribution. Landslide susceptibility was evaluated using a predicted map of probability. Zones with high and medium susceptibility to landslides make up 38.8 % of the study area and are located mostly south of the Sera River Basin and along streams.  相似文献   

Isotopic tracers for water masses in the coastal region of eastern Hokkaido     

Sachiko Oguma  Tsuneo Ono  Akira Kusaka  Hiromi Kasai  Yasuhiro Kawasaki  Tomonori Azumaya 《Journal of Oceanography》2008,64(4):525-539

In this study we used two stable isotopes, δ¹³C and δ¹⁸O, for water mass classification in the coastal region off eastern Hokkaido. δ¹³C* values, which were corrected for the biological effect, and δ ¹⁸O values up to 300 m depth suggested that the isotopic character of the onshore and offshore water in the southern Okhotsk Sea, the Nemuro Strait and the western North Pacific could be explained by the mixing of three source waters: the Oyashio water (OYW), Soya Warm Current water (SWCW) and East Sakhalin Current water (ESCW). In summer, δ ¹³C*-δ ¹⁸O plots indicated mixing between SWCW from the southern Okhotsk Sea and OYW in the Pacific coast of southeastern Hokkaido, while temperature-salinity plots of the onshore water showed minimal difference from the offshore OYW. In winter, on the other hand, the mixed water of ESCW and OYW (or SWCW) appeared in the Pacific coastal region, distributed as cold, low salinity onshore water. Finally, we estimated mixing ratios of OYW, SWCW and ESCW in the coastal region of western North Pacific using their mean values of δ ¹³C* and δ ¹⁸O as endmembers. These results suggest seasonal and yearly changes of water mass combination en route from the southern Okhotsk Sea to the western North Pacific.  相似文献   

Seasonal variation in Tsushima Warm Current paths over the shelf off the San’in coast,Japan     

Akihiko Morimoto  Yutaka Isoda  Tatsuji Tameishi  Shimpei Moriwaki 《Continental Shelf Research》2009,29(11-12):1437-1447

Using long-term sea surface temperature (SST) and acoustic Doppler current profiler (ADCP) data, we examined variations in the current axis of the Tsushima Warm Current (TWC) off the San’in coast of Japan, near the entrance to the Japan Sea. There were large horizontal temperature gradients along the shelf edge in the southwestern Japan Sea from October to May, suggesting that the second branch of the TWC appears not only in spring and autumn but also in winter. From the ADCP data analysis, we found that currents with speeds of approximately 20 cm s^?1 and greater appeared around the shelf edge off San’in coast in all seasons. The SST and ADCP data analyses suggested that the second branch of the TWC exists around the shelf edge off the San’in coast throughout the year. This finding differed from those of previous studies. A relatively strong current (speed greater than 15 cm s^?1) appeared on the shore side in all seasons, except at line W in winter. This current might be the first branch of the TWC. The first branch seemed to occur around in 100 m isobaths, but shifted northward and southward because the bottom topography around lines W and M was relatively flat and the shelf was broad. The first branch was very obscure, and it was difficult to define the two branches of the TWC off the San’in coast from the seasonally averaged vectors. However, snapshots of current distribution derived from the ADCP data clearly showed these branches. Hence, both the first and second branches might occur throughout the year off the San’in coast.  相似文献   

The anisotropy of cosmic ray arrival directions around 10 eV     

N. Hayashida  M. Nagano  D. Nishikawa  H. Ohoka  N. Sakaki  M. Sasaki  M. Takeda  M. Teshima  R. Torii  T. Yamamoto  S. Yoshida  K. Honda  N. Kawasumi  I. Tsushima  N. Inoue  E. Kusano  K. Shinozaki  N. Souma  K. Kadota  F. Kakimoto  K. Kamata  S. Kawaguchi  Y. Kawasaki  H. Kitamura  Y. Matsubara  K. Murakami  Y. Uchihori  H. Yoshii 《Astroparticle Physics》1999,10(4):125-311

Anisotropy in the arrival directions of cosmic rays with energies above 10¹⁷ eV is studied using data from the Akeno 20 km² array and the Akeno Giant Air Shower Array (AGASA), using a total of about 114 000 showers observed over 11 years. In the first harmonic analysis, we have found a strong anisotropy of 4% around 10¹⁸ eV, corresponding to a chance probability of 0.2% after taking the number of independent trials into account. with two-dimensional analysis in right ascension and declination, this anisotropy is interpreted as an excess of showers near the directions of the Galactic Center and the Cygnus region.  相似文献   

地闪回击的微秒级辐射场特征及近地面连接过程分析   总被引：14，自引：6，他引：8  

郄秀书  郭昌明 《高原气象》1998,17(1):44-54

利用１μｓ时间分辨率的慢天线电场变化仪在甘肃中川地区雷暴过程中测量得到的大量地闪辐射波形地地闪回击辐射场特征及回击的慢前沿过程进行分析,发现１８次正地闪和８５次负地闪产在周前沿过程上升时间为１９．２μｓ和９．４μｓ,８４次负地闪继后回击的前沿过程为４．３ μｓ。ＹＹ ＵＤＡ Ｏ ３．１μ;  相似文献   

中国内陆高原正极性雷电的观测实验研究   总被引：20，自引：7，他引：13  

刘欣生  郭昌明 《高原气象》1998,17(1):1-9

叙述了１９９７年夏季中日两国科学家在甘肃平凉地区合作进行的有关正极性雷电的综合观测实验情况,包括地布局,所采用的技术手 取得的主要结果。实验中采用人工引发雷电技术并取得了两次成功,其中一次是利用“空中解发”方式,即火箭拖带的细钢丝下端不直接接地,而是通过一段绝缘尼龙线与接地的另一段细钢丝相连。用这种方式可以更真实地再现自然雷电的初始过程。实验中观测到了空中导线两端先导的双向传输现象;电流、电场变化  相似文献   

Short-period interplanetary and polar magnetic field variations     

K. Kawasaki  F. Yasuhara  S.-I. Akasofu 《Planetary and Space Science》1973,21(10):1743-1755

It is shown that the dependence of the variations of vertical component of the polar cap magnetic field on the sector structure (actually, the azimuthal or Y component) of the interplanetary magnetic field as first discovered by Svalgaard (1968) and Mansurov (1969) extends to variations as brief as 1 hr or even less. The relation between sector structure dependent variations and substorm fields as indicated by the southward-directed component of the interplanetary magnetic field is investigated by comparing brief variations over selected intervals of time. The independence of the variations of the polar cap vertical and horizontal components suggests that there are at least two different current systems which produce brief variations in the polar cap. One of the current systems is related to the substonn field; the other is strongly seasonally dependent and is confined to the dayside sector of the Earth.  相似文献   

A note on the DP-2variation     

S.-I. Akasofu  F. Yasuhara  K. Kawasaki   《Planetary and Space Science》1973,21(12):2232-2238

It is shown that a significant part, if not all, of the DP-2 variation can reasonably be explained by the combined effect of the equatorward expansion of the permanent S_q^p current system and its enhancement. Both phenomena are now found to be controlled by the northsouth component of interplanetary magnetic field. Thus, it is concluded that the DP-2 variation arises from a modulation of the permanently existing S_q^p current system by the interplanetary magnetic field, rather than by an intermittent growth of a particular type of current system.  相似文献   

Comments on the paper ‘interplanetary origin of electric fields in the magneosphere’ by A. Nishida     

K. Kawasaki 《Astrophysics and Space Science》1973,24(2):449-454

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