Acoustic emission （AE） technique is a useful tool for investigating rock damage mechanism, and is used to study the temporal-spatial evolution process of microcracks during the similar pillar material experiment. A ...Acoustic emission （AE） technique is a useful tool for investigating rock damage mechanism, and is used to study the temporal-spatial evolution process of microcracks during the similar pillar material experiment. A combined AE location algorithm was developed based on the Least square algorithm and Geiger location algorithm. The pencil break test results show that the location precision can meet the demand of microcrack monitoring. The 3D location of AE events can directly reflect the process of initiation, propagation and evolutionary of microcracks. During the loading process, stress is much likely concentrated on the area between pillar and roof of the specimen, where belongs to danger zone of macroscopic failure. When rock reaches its plastic deformation stage, AE events begin to decrease, which indicates that AE quiet period can be seen as precursor characteristic of rock failure.展开更多
Minjingu Phosphate Rock （MPR） from Northern Tanzania and the Ikutha Phosphate Rock （IPR） found in Central-Southeast Kenya are well documented as potential sources of phosphorous （P） available in East Africa. On-...Minjingu Phosphate Rock （MPR） from Northern Tanzania and the Ikutha Phosphate Rock （IPR） found in Central-Southeast Kenya are well documented as potential sources of phosphorous （P） available in East Africa. On-farm trials in phosphate-deficient soils in Western Kenya demonstrated MPR to be as effective as triple superphosphate （TSP） - 20% P, at equal P rates. The aim of this work is to determine the distribution of phosphorus in these phosphate rocks （PRs）. The different phosphorus fractions were extracted using the modified Williams extraction procedure and analysis carried on a UV/VIS spectrometer （SHIMADZU UV-220-02 and NOVASPEC II）. The analysis showed that the most abundant form of phosphorus in the phosphate rocks was the Inorganic Phosphorus （IP） contributing 74.20% of total phosphorus （TP） for Minjingu, and 83,28% of total phosphorus for Ikutha phosphate rock.展开更多
基金Projects (2013BAB02B01, 2013BAB02B03) supported by the Key Projects in the National Science & Technoogy Pillar Program During the Twelfth Five-Year Plan PeriodProjects (51274055, 51204030, 51204031, 51109035) supported by the National Natural Science Foundation of ChinaProjects (N110301006, N110501001, N110401003) supportecd by the Fundamental Research Funds for the Central Unviersity, China
文摘Acoustic emission （AE） technique is a useful tool for investigating rock damage mechanism, and is used to study the temporal-spatial evolution process of microcracks during the similar pillar material experiment. A combined AE location algorithm was developed based on the Least square algorithm and Geiger location algorithm. The pencil break test results show that the location precision can meet the demand of microcrack monitoring. The 3D location of AE events can directly reflect the process of initiation, propagation and evolutionary of microcracks. During the loading process, stress is much likely concentrated on the area between pillar and roof of the specimen, where belongs to danger zone of macroscopic failure. When rock reaches its plastic deformation stage, AE events begin to decrease, which indicates that AE quiet period can be seen as precursor characteristic of rock failure.
文摘Minjingu Phosphate Rock （MPR） from Northern Tanzania and the Ikutha Phosphate Rock （IPR） found in Central-Southeast Kenya are well documented as potential sources of phosphorous （P） available in East Africa. On-farm trials in phosphate-deficient soils in Western Kenya demonstrated MPR to be as effective as triple superphosphate （TSP） - 20% P, at equal P rates. The aim of this work is to determine the distribution of phosphorus in these phosphate rocks （PRs）. The different phosphorus fractions were extracted using the modified Williams extraction procedure and analysis carried on a UV/VIS spectrometer （SHIMADZU UV-220-02 and NOVASPEC II）. The analysis showed that the most abundant form of phosphorus in the phosphate rocks was the Inorganic Phosphorus （IP） contributing 74.20% of total phosphorus （TP） for Minjingu, and 83,28% of total phosphorus for Ikutha phosphate rock.
