No abstract

The technology of mining without coal pillar is popular in many mine, though it can improve the recovery rate, it aggravate the air leakage of gob. Because of the ignorance about oxidation in gob, so it is very difficult to know the true value. When we make the test, we find computer can do it that simulation is consistent with reality overall. The article simulate the velocity field and oxygen concentration by finite element method, so divide the ‘three zones’ of gob and analysis the differences before and after plugging, we can see the huge impact of air leakage. So if we want to prevent the Spontaneous Combustion in mining without coal pillar, it is necessary to use the plugging technology.

No abstract

The emergence of pillar-free pillar technology instead of coal pillar technology has raised new requirements for safe production of coal mine. Based on the analysis of gas source, the effects of total pressure change, air flow and main fan stop on gas emission were expounded respectively. At the same time, a concrete analysis was made for the non-pillar mining. It was pointed out that air leakage is the influential factor of gas emission of the key factors.

Summary As an energy storage component of an electric vehicle, the battery pack is subject to continuous vibration when working. It is very important to analyze the dynamic characteristics of the battery pack through finite element method (FEM) for safety concerns. However, because of the complication of structure and the number of parts in a battery pack, it is impractical to develop an accurate FEM model. Thus, simplified methods are always applied for modeling. Because battery modules are the most complicated parts and make up the majority of proportion in a battery pack, it is the key to simplification. Using multibody models, this research proposes a simplified method for soft‐connected battery modules, which can be applied to the battery pack FEM model, accurately calculate the dynamic characteristics of a battery pack, and use less computing resources compared with traditional simplified methods. A practical battery pack structure is modeled using this method. Compared with the traditional ones, this method reduces 90% nodes and 97% meshes, excluding the influence of battery pack enclosure, and consumes 40% less memory during calculation. This method also has higher computing efficiency for larger battery packs with more battery modules. The simulation results are well matched with experimental results, which indicate the universality of the simplified model.