Changes in active functional groups during low-temperature oxidation of coal

Using Fourier Transform Infrared (FTIR) combined with an adiabatic oxidation test, temperature-programmed oxidation and gas analysis, we studied the changes of active functional groups during low-temperature oxidation of lignite, gas coal, fat coal and anthracite. During slow low-temperature heat accumulation, aliphatic hydrocarbons, such as methyl and methylene, are attacked by oxygen atoms absorbed by pores on coal surfaces, generating unstable solid intermediate carbon-oxygen complexes, which then decompose into gaseous products (CO, CO2) and stable solid complexes. At the accelerated oxidation stage, the stable complexes begin to decompose in large amounts and provided new active sites for further oxidation, while the aliphatic structures gained energy and fell from the benzene rings to produce CxHy and H2.

Study of time-domain digital pulse shaping algorithms for nuclear signals

With the development on high-speed integrated circuit,fast high resolution sampling ADC and digital signal processors are replacing analog shaping amplifier circuit.This paper firstly presents the numerical analysis and simulation on R-C shaping circuit model and C-R shaping circuit model.Mathematic models are established based on 1st order digital differential method and Kirchhoff Current Law in time domain,and a simulation and error evaluation experiment on an ideal digital signal are carried out with Excel VBA.A digital shaping test for a semiconductor X-ray detector in real time is also presented.Then a numerical analysis for Sallen-Key(S-K) low-pass filter circuit model is implemented based on the analysis of digital R-C and digital C-R shaping methods.By applying the 2nd order non-homogeneous differential equation,the authors implement a digital Gaussian filter model for a standard exponential-decaying signal and a nuclear pulse signal.Finally,computer simulations and experimental tests are carried out and the results show the possibility of the digital pulse processing algorithms.

Huge thick conglomerate movement induced by full thick longwall mining huge thick coal seam

A discrete elemental method was used to study the thickness of conglomerate layer in a full thick seam mining activities under the influence of the law, pointing out the thickness of the conglomerate at different seam mining, and during the destruction and instability of existing state of laws. At 21141 thick seam mining, the face toward the direction of separation between the thick layer of conglomerate rock and the next bit after reaching its maximum capacity due to pull from the bottom of the plastic zone, formed a stratified and hierarchical down collapse. The shape of caving area is a ''triangular block'', the length of the plastic zone and face advancement from the linear fit between the height of the plastic zone and the advancing face is a quadratic function of distance, while the top layer of thick gravel layer is the overall bending subsidence trend. Tilting the direction of the face, a thick gob of collapsed conglomerate layer is formed in the coal gob entity on both sides of the thick conglomerate at the top of the overall fracture morphology performance, thus forming a mutual extrusion of articulated block structure. The instability, separation and balance of the thick conglomerate layer in the hinged block stope stress leads to abnormal occurrence of rock burst induced by face as the major factor in the accident. This research reveals the form of stress distribution in the destroyed layer of the thick conglomerate rock, analyzes the stope law of coupling for the pressure burst behavior law for the mining work face, and the choice of preventive measures to provide a theoretical basis and implementation.

Establishment and application of drilling sealing model in the spherical grouting mode based on the loosing-circle theory

There are quite a few studies that have been done on borehole sealing theory both domestically and internationally.The existing researches usually consider drilling of the surroundings as a dense homogeneous elastic body which does not meet the characteristics of real drilling of the fractured body.Based on the loosing-circle theory and analyses of the surrounding rock stress field,cracks and seepage fields,combined with Newtonian fluid spherical grouting model,we deduced the dynamic relationship between the seepage coefficient and rock or grouting parameters of the drilling sealing fluid mode of spherical fissure grouting.In this experiment,mucus was injected in the simulated coal seam and the permeability coefficient of the sealing body was calculated by using the model.To verify the validity of the model,the calculated sealing body number was compared with the extreme negative pressure that the sealing body could withstand.The theoretical model revealed the drilling sealing fluid mechanism,provided a method for the quantitative calculation of the drilling sealing fluid effect by grouting mode and a reference for the subsequent research of sealing mechanism.