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The rheological properties of cement grouts are significantly affected by the changes of the time and the water-cement ratio, which determine the diffusion state of grouts in rocks and soils and influence the outcome of projects. In this study, Portland cement grouts with water-cement ratios of 0.50, 0.55, 0.60, 0.65, 0.70, and 0.75 at six moments, including 0 minutes, 5 minutes, 10 minutes, 20 minutes, 30 minutes, and 60 minutes, were evaluated to figure out the comprehensive effect of the time and the water-cement ratio on the rheological properties of power-law cement grouts. The results showed that the water-cement ratio had a great influence on both the consistency coefficient and the rheological index of the power-law cement grouts. The former appeared to have a downward trend with the increase of the water-cement ratio, and the latter appeared to have an upward trend. There was a rising tendency between the time and the consistency coefficient, while the rheological index was less affected by time. The difference between its maximum and minimum values was within 5%. Combined with the perspectives of statistical theory, practical applicability, and accuracy, the exponential model was the optimal model for showing the relationship between the comprehensive effects of the time, water-cement ratio, and consistency coefficient of the power-law cement grouts. The linear model was the optimal model of the rheological index based on the comprehensive effect of time and the water-cement ratio. Based on this, a power-law rheological equation with consideration of the comprehensive effect of time and water-cement ratio was established. The research results could not only improve the rheological theory of power-law cement grouts but also provide technical support for engineering practice.

To explore the ignition and combustion characteristics of tetramethylammonium octadecahydro-eicosaborate ((Me4N)2 B20H18), the compound was obtained by the oxidation of decahydrodecaborate anion, and its combustion heat was measured using an oxybomb calorimeter, and a high-speed camera and infrared thermal imager were used to record the flame phenomenon and the surface temperature on the combustion process of the sample. In combination with the pyrolysis behaviors of the compound in nitrogen and air atmospheres, the combustion process of the (Me4, N)2, B20, H18 was evaluated. The results show that the actual density of the (Me4, N)2, B20 was measured at 0.96 g/cm³, and the (Me4, N)2, B20 exhibits high thermal stability, which decomposes at above 250°C in the nitrogen atmosphere. While in the air atmosphere, an evident mass increment was present at 300°C after a mass loss at 240 - 300 °C. The combustion heat of the (Me4, N)2, B20 is 55.5MJ/kg. This compound presents good ignition combustion performance, and it burns in air with a green characteristic flame. Its surface temperature can reach 1 100°C during the combustion process. [ABSTRACT FROM AUTHOR]

The process of fault activation and sliding induced by deep continuous mining is characterized by grey system. The GM (1, 1) grey prediction model is established based on the field measurement data of fault activation slip induced by deep mining in a copper mine. By comparing the predicted and measured slip values of faults, the model has high accuracy. The grey prediction model of fault activation slip is used to predict the future four phases of fault slip. The growth rate of F2 fault slip is fast, which is consistent with the actual situation in the field. The research results are of great significance to the prediction of active slip under the influence of complex deep mining. [ABSTRACT FROM AUTHOR]

In order to study the process of large-scale overlying strata collapse under the influence of mining in a certain mining area on the basis of the study of macroscopic rock mechanics parameters, the dynamic development process of large-scale overlying rock collapse and caving under the condition of continuous excavation and unloading in different middle sections is analyzed by using the discrete element method program 2D-Block. The simulation results show that with the continuous mining of the deep orebody, the overlying rock mass cave and collapse scope increases gradually, the collapse of overburden strata has a certain hysteresis. The maximum collapse range of overburden strata are respectively 25 m, 42 m and 42 m after 13, 14 and 15 middle sections are mined; the maximum collapse range of overlying rock are respectively 76 m, 97 m and 110 m after 16, 17 and 18 middle sections are mined. [ABSTRACT FROM AUTHOR]

In order to understand the ignition and combustion characteristics of tetraethylammonium dodecahydrododecaborate, laser ignition experiments were conducted on a sample with an equivalent diameter of 1.11 mm to determine its ignition and combustion parameters. Combining with the pyrolysis behaviors in both nitrogen and air atmospheres achieved by thermogravimetric analysis/mass spectrometry, the combustion mechanism of tetraethylammonium dodecahydrododecaborate was also e-valuated. The results show that tetraethylammonium dodecahydrododecaborate, which cracks at above 300°C in both nitrogen and air atmosphere, has a good thermal stability. During the cracking process, the material is oxidized simulaneously and oxidized strongly and gain weight when heated to 650°C. This compound can be ignited easily in air, and its ignition delay time is determined to be 45.8 ms with the ignition power density of 4.72 X 106 W/m², and the total burning time is 2.467 s. The surface temperature is 1 600-1 800°C during the combustion process. It is proposed that, in the combustion process of tetraethylammonium dodecahydrododecaborate, both H2 release and skeleton cracking occur, and the combustion of the gaseous hydrocarbon compounds formed from skeleton cracking could lead to obvious traces of smoke. [ABSTRACT FROM AUTHOR]

In the extraction process of LBP features, most consumption of time and memory were paid for clustering. In order to address these problems, an improved local binary algorithm for image categorization was proposed. The algorithm replaced decimal system encoding LBP with binary descriptor. Meanwhile, Hamming distance was employed rather than Euclidean metric for features clustering. The multi-scale LBP features was flued for a new local binary descriptor. The result of the experiment on the PASCAL VOC 2007 dataset showed that the adopted local binary descriptor was better than the classical LBP, specifically for time consumption. [ABSTRACT FROM AUTHOR]