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1,370 results on '"Zhang, Nong"'

3. Failure characteristics of surrounding rock in deep coal roadway with composite roof and cross-boundary anchor-grouting graded continuous support technology

Author

LI Jian, LI Yongle, XIE Zhengzheng, ZHANG Nong, GUO Feng, LIN Xuezhen, and CHEN Qinghua

Subjects
roadway, deep part, composite roof, graded continuous support, thick-layer anchored, Mining engineering. Metallurgy, TN1-997
Abstract

To solve the problem of large deformation of roadway with deep composite roof, based on the material roadway of 3205 working face in Xin’an Coal Mine as the engineering background, the deformation and failure characteristics of roadway with composite roof and its influencing factors were analyzed by combining field analysis and UDEC numerical simulation. Based on the principle of thick layer anchoring of roadway roof, a technical scheme of graded continuous cross-boundary anchoring was proposed. The feasibility of the new scheme is verified by field monitoring and simulation results. The results show that the initial support strength is very important for roadway maintenance. The optimized support scheme can effectively control the deformation of roadway surrounding rock, and the deformation of roof and two sides is reduced by 64% and 63% respectively. The maximumcrack depth decreased from 9.56 m to 3.26 m. The new support scheme constructs the anchor rock beam structure with thick and stable roof, which can maintain the long-term stable bearing capacity of the roadway.

Published
2024
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21. Beneficial Investigation of Extended-Range Electric Powertrains with Dual-Motor Inputs and Multi-Speed Transmission

Author

Nguyen, Cong Thanh, Walker, Paul D., and Zhang, Nong

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

This paper comparatively investigates the performance of extended-range electric powertrains composed by integrating dual-motor inputs, multi-speed transmission, and engine in either series or parallel connection. Two configurations, namely dual-motor series powertrain (DMSP) and dual-motor parallel powertrain (DMPP), feature the same electric drivetrain of two downsized motors and a four-speed transmission, but their range extenders are fundamentally different. While the DMSP consists of a range extender formed by an engine-generator unit, the DMPP connects the engine through a frictional clutch. This study starts with the parameter selection that guarantees the equivalent dynamics ability of all configurations. Mathematic models are second established in detail. A model predictive control-based energy management strategy is third presented. Since the recommended configurations aim for bus application, the driving cycle CBDC and ECE15x5 are chosen for simulation. Performance indexes used for comparison include electric consumption, fuel consumption, and emissions (hydrocarbon, carbon monoxide, nitrogen oxides, and particulate matter). Compared to the conventional single-motor series powertrain, the DMSP improves all the indexes significantly, while the DMPP decreases fuel consumption further but increases most noxious exhaust emissions., Comment: 23 pages, 13 figures

Published
2019

38. Asymmetric deformation characteristics of steep coal-rock interbedded roadway and cross-boundary anchor-grouting combined differential support technology

Author

DONG Taihua, XIE Zhengzheng, ZHANG Nong, LIU Huajun, WANG Jin, and KANG Hong

Subjects
steeply inclined coal seam, coal-rock interbedded, asymmetrical deformation, differential support, cross-boundary, anchor-grouting, Mining engineering. Metallurgy, TN1-997
Abstract

In order to solve the problem of asymmetric large deformation control of steep coal seam roadway, taking steep coal-rock interbedded roadway in Zhaojiaba Mine as the engineering background, the asymmetric deformation mechanism of steep coal seam roadway was discussed by using the research methods of field observation, theoretical analysis and numerical simulation, and the cross-border bolt-grouting differential support technology was proposed based on the cross-border support principle. The occurrence of steep coal strata leads to the unsymmetrical stress distribution in surrounding rock of roadway, which leads to the shear slip deformation of coal and rock at the top of arc, while the deformation at the top of straight inclined coal is relatively small. Different anchorage lengths and bolting-grouting methods are used to establish the differentiated cross-border support forms on both sides, and the equivalent thick anchor bearing structure of surrounding rock of roadway is constructed. The simulation shows that the surrounding rock stress is optimized, the deformation of roadway is significantly reduced, the settlement of arc roofis reduced by 39.0%, and the convergence of the side wall is reduced by 41.6%. Field industrial verification shows that the maximum crack depth of arc roof is generally reduced from 3.88 m to 1.50 m, which is 61.3% lower, the crack development depth of straight inclined roof is reduced by 47.6%, and the surrounding rock control effect is improved.

Published
2022
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