The existing opportunistic protocols of Delay Tolerant Network (DTN) occupy much storage and the prediction-based protocols need to calculate and spread much predication information and the scheduling protocols can't accommodate to huge complex network. This paper analyses and summarizes the existing DTN protocols and proposes a new DTN routing protocol called CRHC which is based on hierarchical forwarding and cluster control mechanism. CRHC can efficiently control the routing overhead locally and forward message quickly across the whole network. At last, we compare the CRHC with the classic Epidemic and SMART protocol through OPNET simulation. The result demonstrates that the CRHC can effectively reduce the delivery delay and improve the successive delivery rate.

The mining of underground coal resources often results in extensive damage to the ground surface, particularly in China, which has a large amount of coal resources. However, the laws of surface damage caused by the mining of deep and shallow underground coal resources are relatively different. This study analyzes the difference in surface damage induced by deep and shallow mining and its mechanism by field measurement and similar material simulation experiments. Surface damage is mainly manifested in the form of cracks, which can be categorized as permanent and dynamic cracks. Permanent cracks occur above the mining boundary of shallow and deep coal mines. Dynamic cracks (including dynamic stretching cracks and stepped cracks) only appear above the goaf in shallow mining. This disparity is due to the fact that strata movement in deep mining occurs in a “three zones” mode, with the failure height of strata increasing with the mining degree in an “S” shape. However, rock strata movement in shallow mining follows a “two zones” mode, with the failure height of rock strata increasing exponentially with the mining degree. Thus, the rock strata are prone to slide and become unstable in the form of benched rock beams, producing dynamic cracks, such as stepped cracks on the surface. This research improves the existing mining subsidence theory and provides technical support for relevant mines to take targeted treatment measures.

High-strength mining has the characteristics of shallow buried depth, large mining height, and fast mining speed. Under the condition of high-strength mining, the overburden moves violently and the surface damage is serious. It has caused serious ecological security problems in the mining area. In order to solve this problem, it is necessary to adopt the technology of restoration while mining. The key to the effective implementation of this technology is to clarify the real-time distribution law and generation mechanism of surface damage. In this paper, field investigation and the theoretical analysis method are used for related research. The results show that the surface strenuous move duration is long, the strenuous move area is large, and the surface discontinuous deformation is fully developed. With the characteristics of stepped crack lags behind the location of the working face, the stepped crack spacing and periodic weighting interval are equivalent. Through discussion and analysis, it is found that the cause of serious damage is the strata movement mode of high-strength mining in “two zones” mode. Under the “two zones” mode, the roof has easy-to-slip instability, the bedrock is completely broken along the direction of the bedrock breaking angle, and the weak anti-disturbance ability of the loose layer leads to the surface becoming severely damaged. The research results can provide reference for the formulation of follow-up ecological real-time restoration measures in similar mines.

According to traditional concepts, the movement of overlying strata and surface damage caused by coal mining in horizontal coal seams are symmetrical in terms of spatial distribution. However, in a lot of engineering practices, this symmetry has not been discovered. We often use the symmetry function to establish the profile prediction function of the surface damage, which results in a large difference between the prediction result and the actual situation. To solve this problem, this paper takes subsidence velocity as an example. Firstly, the spatial distribution functions of subsidence velocity on both sides were deduced theoretically. Through comparison, it is found that the change rate of the spatial distribution curve of the coal pillar side subsidence velocity is smoother than that of the goaf side and the subsidence velocity curves are skewed to the left. Secondly, based on the idea of lossless propagation of harmonic waves and idealizing the propagation environment, the spatial propagation relationship of surface subsidence velocity in the time domain is established. Then, the Box–Cox transform function is introduced to improve the normal distribution probability density function, and a new dynamic subsidence prediction model based on the Box–Cox transformation is obtained, which is suitable for the full mining stage. The model is tested by practical cases, the prediction accuracy is better than 7%, and the prediction results can meet the needs of engineering prediction accuracy (10%). The results of this research can enrich the existing subsidence prediction theory and provide theoretical and technical support for the prediction of dynamic surface damage caused by similar mining.