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Now showing items 17 - 23 of 23

  • Fundamental Study on Assessment of Soil Erosion by the USLE Method at Rehabilitation Area in Indonesian Coal Mine

    Inoue, Naoya   Hamanaka, Akihiro   Shimada, Hideki   Sasaoka, Takashi   Matsui, Kikuo  

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  • Involvement of Kv channel subtypes on GABA release in mechanically dissociated neurons from the rat substantia nigra.

    Shimada, Hideki   Uta, Daisuke   Nabekura, Junichi   Yoshimura, Megumu  

    The seven members of Shaker-related K(+) channel family, which are known to regulate membrane excitability and transmitter release, have been identified in the CNS. It is known that the substantia nigra pars reticulata (SNr) receives GABAergic inputs mainly from the striatum and sends GABAergic outputs to the thalamus. An immunohistochemical study shows that the Kv1 family, particularly Kv1.4, is expressed in the SNr, while it is reported that Kv1.2 mRNA is detected in the striatal neurons. Therefore, which Kv channels may be involved in the release of GABA in the SNr remains still controversial. To address this issue, we tested the effects of various K(+) channel blockers on the synaptic transmission using mechanically dissociated SNr neurons known as "synaptic bouton preparation", that retained functional presynaptic nerve terminals which enable us to examine miniature inhibitory postsynaptic currents (mIPSCs) by conventional whole-cell patch clamp recordings. Based on the sensitivities of mIPSCs to the Kv channel blockers, we concluded that Kv channels, in particular Kv1.2 subunit play the most significant role in the release of GABA at the presynaptic terminals projecting to the SNr neurons.
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  • Stability Control of Retained Goaf-Side Gateroad under Different Roof Conditions in Deep Underground Y Type Longwall Mining

    Zhang, Zhiyi   Shimada, Hideki   Sasaoka, Takashi   Hamanaka, Akihiro  

    Stability of the retained goaf-side gateroad (RGSG) is influenced mainly by the movements of the roof strata near coal seam after coalface passes by. To make effective controlling technology for the stability of the RGSG, we analyze the roof structure over the RGSG to illustrate the mechanism causing the RGSG instability under different roof conditions. We then examine the dynamic evolution of the deformation and abutment stress in the rock surrounding the RGSG during coal seam mining, using the FLAC3D numerical software to reveal the instability characteristics of the RGSG under different roof conditions. Next, corresponding stability controlling technologies for the RGSGs are proposed and tested in three typical deep underground coalmines. Results show that: sink and rotation of the roof cantilever over the RGSG impose severer influence on the stability of the RGSG. The RGSG suffers disturbances three times during the coal-seam mining, and the deformation and abutment stress in the rock surrounding the RGSG increase significantly when the main roof becomes thicker and the immediate roof becomes thinner. Staged support technology involving grout cable bolts has better controlling results of the RGSG stability than that composed of conventional rock bolts, when the RGSG is beneath weak immediate roof with large thickness. Roof structure optimizing technology involving pre-split technology can improve the stability of the RGSG effectively when the RGSG is covered by hard main roof with large thickness directly.
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  • Development of a new covering strategy in Indonesian coal mines to control acid mine drainage generation: a laboratory-scale result

    Shimada, Hideki   Kusuma, Ginting Jalu   Hiroto, Koh   Sasaoka, Takashi   Matsui, Kikuo   Sayoga Gautama, Rudy   Sulistianto, Budi  

    The waste dump of sulphide-containing rocks is one of the potential acid mine drainage sources, since it contains a huge amount of readily oxidised sulphide mineral, due to its exposure to air and water. The application of the dry cover system is regarded as one of the best practices since it prevents acid mine drainage of the waste rock dump at the surface coal mine. However, the implementation of the dry cover system in field practice has faced several obstacles due to the limited number of cover materials. The nature of geological condition is considered to be a controlled issue, whilst the problem is the mining method and equipment size. This article describes the acid generation mechanism and its control, application of cover system and the problems that are faced in Indonesian coal mines, whilst discussing the preliminary laboratory results of multi-layer cover systems. It finally proposes a new covering strategy in an attempt to overcome the problem.
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  • Interaction between physical and chemical weathering of argillaceous rocks and the effects on the occurrence of acid mine drainage (AMD)

    Matsumoto, Shinji   Shimada, Hideki   Sasaoka, Takashi  

    The disintegration of rocks by weathering plays an important role in the occurrence of Acid Mine Drainage (AMD), which is the environmental problem caused by the exposure of sulfide minerals to water and oxygen. The weathering of rocks is, generally, classified into physical or chemical weathering. However, there are few studies that focus on the complex interaction between physical and chemical weathering of rocks and on the effects of the interaction on the occurrence of AMD. This paper elucidates the complex interrelation between physical and chemical weathering of rocks as well as the progress of AMD through leaching test and weathering test with argillaceous rocks taken in open-cast coal mine in Indonesia in addition to sample analysis before and after the wetting and drying cycle: the rock samples were exposed to oxygen and water during the cycle. The results indicated that the argillaceous rocks which consist of sulfide and/or sulfate caused chemical weathering with micro-cracks on the surface of rocks through the dissolution of soluble iron and sulfur during the occurrence of AMD. Additionally, physical weathering of rocks due to clay minerals was accelerated by chemical weathering with the development of cracks with the occurrence of AMD in the argillaceous rocks containing kaolinite and pyrite. Although weathering of rocks also accelerated AMD, it was concluded that the sulfur content, the form of sulfur and iron in rocks, and the supply of oxygen significantly contributed to the occurrence of AMD.
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  • A Synthetic Solution for Identification and Extraction of the Effective Microseismic Wave Component Using Decomposition on Time,Frequency,and Wavelet Coefficient Domains

    Zhang, Mingwei   Meng, Qingbin   Liu, Shengdong   Shimada, Hideki  

    To reduce noise components from original microseismic waves, a comprehensive fine signal processing approach using the integrated decomposition analysis of the wave duration, frequency spectrum, and wavelet coefficient domain was developed and implemented. Distribution regularities of the wave component and redundant noise on the frequency spectrum and the wavelet coefficient domain were first expounded. The frequency threshold and wavelet coefficient threshold were determined for the identification and extraction of the effective wave component. The frequency components between the reconstructed microseismic wave and the original measuring signal were compared. The noise elimination effect via the scale-changed domain decomposition was evaluated. Interaction between the frequency threshold and the wavelet coefficient threshold in the time domain was discussed. The findings reveal that tri-domain decomposition analysis achieves the precise identification and extraction of the effective microseismic wave component and improves the reliability of waves by eliminating the redundant noise. The frequency threshold and the wavelet coefficient threshold on a specific time window are two critical parameters that determine the degree of precision for the identification of the extracted wave component. This research involves development of the proposed integrated domain decomposition method and provides a diverse view on the fine processing of the microseismic signal.
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  • [IEEE 2011 IEEE Consumer Communications and Networking Conference (CCNC) - Las Vegas, NV, USA (2011.01.9-2011.01.12)] 2011 IEEE Consumer Communications and Networking Conference (CCNC) - Visualization and control system for wireless network using augmented reality technology

    Shimada, Hideki   Sakamoto, Naoya   Ayaki, Ryota   Sato, Kenya  

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